They're very reliable, a good way to know when a hosting service is good (because 95% of them are a scam in some way) is to go to
www.webhostingtalk.com and search the forums for the company you're thinking of. And read the reviews on them.
The only catch about servage, is that its 37gb per day (which total up to 1110 gb over 30 days) if you exeed 37gb your site will be shut down for the remaining of the day (but lets face it, its almost impossible nowadays to exeed 37gb of bandwidth a day).
As for Shell access, no you dont get it. Its a shared server, so theres more than 1 site on each machine (vs dedicated server) therefor they cant really give out shell access, but you still have access to all the apache comands, which can do almost everything you'd need to do :)