there's no need to go for 300% bg skill unless you're 1 STR build using 7ST avenger.
doc at 100% is sufficient, you just get doc bag which gives +50%doc. - with higher ST & LK you won't be crippled as often as 1 ST & 1 LK builds.
LK is described on wiki so I suggest to go there and also search for it here on forum. The higher luck the better rolls in a short.
if you're using flamer only then 180% bg is sufficient.
by tagging OD you get around 132% in that skill once you read all 10 books from the start, so it's convenient. By doing this you do not have to invest a single SP into OD anymore (unless you want 150% OD perks) and you can invest everything into FA & doc - doc raised to 100 first, then FA to 200.