I teach bass guitar and my students ask me this question all the time.
There is no right answer in terms of a specific instrument. I'd say, when shopping for a bass, look for the following, in this order:
1. Something that feels comfortable in your hands, and to play, sitting and standing
2. Something that looks cool, that you'll be proud rather than embarrassed to be seen with
3. Something that sounds good
Yes, sound is the least important consideration. Why? Because tone is 90% your fingers, 9% your amplifier/effects settings and 1% everything else. A great player can make any piece of shit instrument sound great. Conversely, a crap player will always sound crap no matter what is in their hands. But a bass that feels bad to play will not make you want to play it, and a bass that looks stupid will also discourage you.
I guess budget is also possibly a consideration. I don't believe in expensive instruments when cheap ones can get a comparable sound. If you've got the money to blow, why not, but if you're like me you've got bills, a mortgage and other real world concerns. Some people really like the Squier P-bass and J-bass. Some prefer the slim Ibanez and Yamaha ones, right now I play an Epiphone Thunderbird and I love it, but it's not a bass for everyone. The absolute worst bass I ever owned was a Gibson, I'm so glad I got rid of that hunk of junk, it was so heavy it put my shoulder out and the tone wasn't significantly different to the Yamaha I replaced it with. However, the ultimate test is what feels good for you and since everyone has different physical bodies, everyone like different basses because it's that interaction between the instrument and your body which is going to be the #1 selling point. That's why no-one can ever definitely answer this question.
Oh and for your second question, maybe I'd get a Gibson Thunderbird instead of an Epiphone one. That's only if I had more money than brains though, because the two instruments are identical in every aspect that actually matters.
