First i want to make clear what my take on "street cred" is. Well as the name street credibility implies and from what i could gather from the demo and other official sources, it's the way you are seen by "the street" aka fixers, gangs and corps in relation to your ability to "get things done". High credibility implies greater trust in your abilities thus higher profile missions available and fame across the people looking to hire someone of your particular... talents. With that in mind let's move on to the poll;
(1) and (3) I see this more as a means to an end rather than a goal in itself in relation to your credibility as a mercenary. A combat oriented Solo would no doubt have a higher kill count than a Techie, and a Netrunner would undoubtedly achieve it's objectives often unseen or undetected by enemy enforcers, thus avoiding unnecesary/unwanted combat encounters. However as long as the objective is completed the recompense would be awarded and street cred as well.
✓ (2) it's not only desirable it's only logical that your credibility is directly linked to the number of completed contracts.
✓ (4) This might be a good idea if only to add a bit of ... flavor to the progression and even increase replayability . You can definitely say that doing things with style can have a positive affect on your reputation. How exactly it should work is pretty much up for discussion.
✓ (5) This is pretty much a given at this point (though i personally would not vote for it otherwise). And i guess it serves the "style over substance" angle fairly well..
✓ (6) Yes, undoubtedly. i'd take a well equipped specialist over a poorly equipped one any day. And presumably the good stuff is not easy to obtain, so all the more reason to believe he knows what he's doing thus contributing to his credibility.
(7) Make the clothes bonus not applicable in those zones. Cred is Cred no matter where you are.. you can always "get shit done"
(8) It's a dog eat dog out there. Lying and stealing is Street Rookie 101 and it could serve your reputation with the more.. unsavory types, so with a lack of a multi-variable rep or cred system, no, i don't think you should lose street cred for stuff like this, relationships.. definitely.
(9) Should be able to lose cred when you fail to meet contract requirements. That's up to CDPR on how to make it interesting and not make the player instantly want to reload.
(10) I wouldn't have bothered with writing this if i wasn't. Long post are not my cup o'tea.
Thanks for reading. Have a good one.
TL;DR
2,4,5 and 6