They're active in different ways, I think. The Reddit does better at answering quick questions and discussing the latest news; the forum does better at ongoing in-depth discussions.
I'm answering here because I also tend to prefer forums. I'm skipping questions for people who've played other CCGs because I haven't.
A few cards are bad. A larger number of cards are fairly narrow. Bad cards presumably exist not because they serve a purpose but because designing cards is hard. Narrow cards often appear bad, but I think a fair number of them eventually find a use in a particular decktype or meta. Some of them never do, in which case I think it's an open question whether they just needed some support or were just bad cards after all.
Yes, there are many deck styles, including many combo decks. There is often a problem with one deck style being the strongest in competitive play for too long, but FFG seems to be working on improving that situation.
Chaos Theory Stimshop was my favourite combo-y runner deck for a long time, and I would recommend it to you if the key cards weren't about to rotate. Dyper is a more powerful and combo-y Runner deck. It's still losing a key card to rotation, but the basic idea may survive. On the Corp side, CI7 is the combo-est deck, but it's complex to learn and also has key cards about to rotate. Fashion CI is more rotation-resistant.
It's hard to say. There have definitely been problems recently, but it's quite possible that FFG's delay in addressing them had more to do with having just changed designers than anything else. The new MWL (restricted list) has done a lot to improve the mood of the community in the last week.
FFG definitely doesn't have as many resources for Netrunner as WotC has for Magic, but I think they have done a reasonably ok job overall. I think they may do a pretty decent job with Netrunner in the future, but I don't know that they will.
There's a lot of articles on Stimhack's home page. There are some other blogs and blog-ish sites, such as Fetal AI, Sneakdoor, Run the Net. But there aren't multiple new in-depth articles most weeks.
A lot of the fan-produced content takes the form of podcasts, so if you like podcasts then you'll have a lot more content to enjoy.
Do start with a core set and see if you like the new version, if there are people to play with locally, and so on. Core set only decks aren't very competitive, but the core set does give a good taste of the game in many ways.
Second purchase should probably be Terminal Directive. It's a new expansion that will be released April 27, it will never rotate, it contains cards for four of the seven factions, and it looks to contain some good utility cards to round out the core set. It also has a legacy-game-style campaign.
After that, the usual advice is to buy the other deluxe expansions, starting with the ones that have your favourite factions. There are four of these, they each focus on two specific factions, and they will also never rotate. Data and Destiny is a little different from the other three; instead of focusing on a Runner faction, it introduces three Runner mini-factions, which are kind of fun but can be hard to build around if your collection is very small.
By the time you've digested those, you'll likely have a better idea what data packs you want.
At some point you'll quite possibly want a second core set. And maybe eventually a third, if you really want to own full playsets of the eleven cards that only have one copy in the core set.
There's a rumour going around that they're going to release a new version of the core set soon. If it's true - which I'm not convinced of at all - then I don't think it should stop anyone from buying a core set now, but you might want to delay a second core set for a while. Focus on the deluxe expansions first and I think you'll be fine.
Don't! Don't do it!
There are a few places online trying to sell singles, but because they can only really get them by breaking up the fixed-distribution sets, they always work out to be an awful deal. The economics of a singles market just don't work out for LCGs. In the long run, you will save money by buying full expansions instead of singles. Sorry.
I usually use images from NetrunnerDB. There's also an image export for decklists in the Meteor deck builder, which might be useful if you're making proxies for a whole deck, I guess. I don't know of anything that will put together the layout for printing.
Having a few proxies is pretty widely accepted at casual play nights, partly because most long-time players have one and only one playset of basically every card, so they can build any deck for a tournament but would have trouble building multiple decks at once without proxies. Also because card rarity is not something most players are interested in simulating in a game without it.
I have not. I know discussion of three player variants comes up occasionally, but I don't know of any that have been played much.