All station names are marked both in Chinese and in pinyin (romanized spelling of Chinese name). In a few cases the station name may be an English translation or a partial translation (military museum = junshibowuguan, Tian'anmen East/West come to mind) but certainly you should have no problem recognizing where you are.

Buying tickets is also not going to be a problem. The deal in Beijing is still 2RMB gets you a ticket (actually a one-time use smart card) anywhere on the system with unlimited transfers (*except* the link from the airport to dongzhimen). At most stations there will be a counter where you can buy tickets. At some there are only ticket machines (also easy to use), but usually one of the station staff will be able to help you. Depending on how much travelling you are going to be doing on the metro you could also buy an electronic smartcard (Yikatong see - http://en.wikipedia.org/wiki/Yikatong). This doesn't save you any money on the metro (but does on busses), but does save the inconvenience of having to buy a ticket each time you make a new journey. Just stand by a machine looking helpless and say "yi-ka-tong" and someone will help you buy one. Note you *cannot* buy several "tickets" and use these during your visit - each "ticket" is only valid from that station for that day (possibly also within a certain number of hours - but I am not sure about this).

VPNs can be used to get access Youtube and similar sites, but since Feburary this year the government has turned the blocking-machine up to 11 ... If you already have a VPN account, check with them before you leave about access from China. If not, there are some good suggestions in this thread (note that the free version of the software suggested by moondog will not give you Youtube access - or at least it says that streaming access is disabled - I haven't actually tried this though).

For food if you are eating in a restaurant that serves Chinese food you will be eating with locals Maybe slighter richer locals than at the corner noodle place, but certainly locals. Even at smaller places you can find menus in English (or at least some variant of English), and if not there will most likely be a menu with pictures of many of the dishes (this is almost standard here in all but the smallest places.

Bargaining is indeed required almost anytime that there is no posted/labelled price (and also many times even when it is). You will almost certainly end up paying a higher price than a local could get - but not by so much, unless your bargaining skills are completely useless.