1.why not? In PVE focus should easily hit 7k+ with sweep, watchman has 5-6k merciless slash and countless burn, combat has even higher burst, just try master strike after precise slash, the number will make your day. In PVP damages could be even higher.
2. Anything except for armxxx. Depending on what you want. If you like PVP, then use cyber tech and related gathering skills(plz google them). You will be able to use reusable gerenades, quite powerful. Otherwise you have to buy them through GTN. Anyway, just try something out, and you will find your favorite.
3. I usually bring doc. Some kolto is always good, huh?
4. I haven't got bis yet. For pvp you have to go through posts in pvp forum, to understand "bolster" . But as to me, full conquer is already good enough. For PVE, I think purple 78 should be what you want, they could be purchased from ultimate gear vendor, or through operations.