lol wth, you still play on troy xD?
how'dd you get those =]
on topic:
dont try the +7, it will fail.
if i were you i'dd leave the +5 aswell, unless you got a spare say ... 50m to either get it back to +5 or just leave it =]
if you try the 76 bow, add str / int / atack rating / durability atleast with 5%-10% stones.
if you get low str / int leave it for the time and try to fix the phy atack and reinf first =] they might assimilate the str / int for the better if your lucky

good luck ^__^
EDIT: to add blues, either buy a green stone, or a green tablet.
if you choose the stone, you just press "Y" and click "att.enhancement" put in your bow, and then put in the stone --> click fuse and you will either have the blue, or fail and need an other stone ^^
if you choose a tablet you need to have the elements listed at the bottom of the tablet.
once again you press "Y" and put in the tablet and then the elements needed =] --> click fuse, and you will have a stone ^__^