Probably. Technically, I believe the currently accepted STYLE (not necessarily the same as grammar) is to omit commas before the final element in a series ("x, y and z" not "x, y, and z,") so it could be argued there should be no comma before "etc." in your first question. I still dislike the word "besides," but that is my idiosyncracy, since it is undeniably correct grammar (I prefer using "beside" in all instances, which is also acceptable, but vulnerable to the ambiguity discussed here.)
I do not believe "etc." in this case (perhaps in any case) should fall prey to serial comma conventions. In order to do so, as you note in your example, there would need to be an "and" before it, which doesn't really go with "etc.". If you simply took the comma out it would read (I'm paraphrasing, I don't have the exact words on hand), "using Twitter, posting on Facebook etc." I feel in this case that using the comma is correct regardless of serial comma conventions.
The serial comma is definitely not a matter of grammatical law, as you said. As long as you either consistently use it or consistently don't use it, you're fine. The standard convention even differs from country to country. In Canadian grammar, for example, it is customary to include the serial comma between the last two items of lists. Bread, milk, and cheese. I'm sort of fond of the little bugger myself.
Because, technically, the conjunction "and" is superfluous in lists concluded with "et cetera." I am OK with it either way though.
Honorbound and honored to be Bonded to Mahtaliel Sedai
Last First in wotmania Chat
Slightly better than chocolate.
Love still can't be coerced.
Please Don't Eat the Newbies!
LoL. Be well, RAFOlk.
Last First in wotmania Chat
Slightly better than chocolate.
Love still can't be coerced.
Please Don't Eat the Newbies!
LoL. Be well, RAFOlk.
Grammar junkies
05/10/2011 06:46:31 PM
- 1026 Views
I'm not always sure that I'm correct, but....
05/10/2011 07:04:13 PM
- 716 Views
I didn't see any errors
05/10/2011 07:24:27 PM
- 698 Views
Must ... have ... grammar.
05/10/2011 07:53:34 PM
- 884 Views
For you and Tom as well, the same question about question eight.
05/10/2011 08:33:39 PM
- 1107 Views
Tom can probably give you actual terms and correct rules, but here's my take on it.
05/10/2011 08:43:47 PM
- 657 Views
Er...yes I meant them as a singular idea... *NM*
05/10/2011 08:47:34 PM
- 423 Views
Use them together, and only together, for fifteen years and we can discuss this again. *NM*
05/10/2011 09:32:30 PM
- 355 Views
That makes sense as far as it goes.
05/10/2011 09:02:42 PM
- 691 Views
But do you actually regard them that way?
05/10/2011 09:08:36 PM
- 673 Views
Yeah, pretty much.
05/10/2011 09:25:18 PM
- 636 Views
No, Joel. You're just wrong. Again. Get used to it. We have.
05/10/2011 09:31:21 PM
- 591 Views
I can live with being wrong, at least in the sense of technical error.
05/10/2011 10:06:30 PM
- 682 Views
Let's just pare this down to the bare bones.
06/10/2011 01:37:30 AM
- 542 Views
He made a mistake that I did not recognize as a mistake because I read his words as he intended.
06/10/2011 04:43:39 AM
- 694 Views
You bring up a point that I was researching the other day
05/10/2011 08:53:40 PM
- 734 Views
You guys mean a hyphen, not a dash.
05/10/2011 09:00:25 PM
- 671 Views
You're right of course!
05/10/2011 09:13:44 PM
- 749 Views
I frequently am.
05/10/2011 09:16:38 PM
- 750 Views
So I've noticed.
05/10/2011 09:19:38 PM
- 667 Views
Achtung! Grammatik! :insert Nazi-saluting smiley as the Wehrmacht marches by:
05/10/2011 08:10:45 PM
- 781 Views
Good poll, especially for this site.
05/10/2011 08:11:10 PM
- 769 Views
Re: serial comma.
05/10/2011 08:31:58 PM
- 662 Views
Maybe I was being a little anal there.
05/10/2011 08:35:33 PM
- 626 Views
Re: Grammar junkies
05/10/2011 08:33:06 PM
- 676 Views
People should talk in a way that can be understood, else they are not communicating.
05/10/2011 09:17:37 PM
- 717 Views
Re: "everyone's". ~winky~ *NM*
05/10/2011 09:22:18 PM
- 340 Views
Is it time for my lecture on superfluous apostrophes again?
05/10/2011 09:43:47 PM
- 631 Views
Unsurprisingly, I don't really agree with you at all on this point. :p
05/10/2011 10:29:59 PM
- 699 Views
I do not really think I am "right" on this one so much as "not wrong."
06/10/2011 12:01:36 AM
- 613 Views
But contradictions are inherent in the entire English language!
06/10/2011 01:25:39 AM
- 631 Views
Ghoti. Also, this is why Rebekah and don't argue this any more. *NM*
06/10/2011 04:44:42 AM
- 301 Views
Sure, but not deliberate ones created by grammarians who know better.
06/10/2011 05:40:58 AM
- 630 Views
I'm going to listen to the others.
06/10/2011 06:17:18 AM
- 657 Views
Like I say, I appreciate exceptions when justified (and again, only claiming to be "not wrong." )
06/10/2011 07:26:18 AM
- 551 Views
But you are wrong
06/10/2011 02:17:40 PM
- 683 Views
I disagree.
07/10/2011 12:15:14 AM
- 629 Views
How utterly unsurprising
07/10/2011 02:21:38 PM
- 579 Views
"We want to be nothing if not persistent."
07/10/2011 02:39:19 PM
- 625 Views
Doesn't matter.
07/10/2011 03:12:14 PM
- 675 Views
Perhaps not, but it should, and I am not above being a lone voice crying in the wilderness.
08/10/2011 05:17:35 PM
- 722 Views
What.
06/10/2011 06:17:41 PM
- 725 Views
Those cases are not the same, because those words are already possessive in their own right.
06/10/2011 10:52:06 PM
- 717 Views
if you have trouble understanding my post it is more likely do to typing skills than grammar
05/10/2011 09:31:42 PM
- 633 Views
Likely so; I have the same problem, but usually when writing by hand.
05/10/2011 09:53:08 PM
- 622 Views
#1) I do not use NetSpeak while playing games, texting or using social media.
05/10/2011 11:34:12 PM
- 627 Views
What about NateSpeak? *NM*
06/10/2011 04:01:08 PM
- 316 Views
I did use that once to tell the story of you and CNRedDragon going to see Ice Princess. *NM*
07/10/2011 01:46:50 AM
- 314 Views
I freebase split infinitives on a regular basis.
06/10/2011 01:53:36 PM
- 561 Views