Hey i have a 62 worgen ( warrior) equipped with lvl 60 Field Marshall set (6/6) + 2handed sword (legacy weapon)

my question is...is it worth to have this gear on while leveling and playing battlegrounds at the same time or must this gear be only used in Battleground

Can i play on with this gear until i reach lvl 70 then get those lvl 70 gears from the honor vendors?

i have the armor and shoulder heirloom

You can use it in leveling as well as bgs. It would be a better idea to upgrade the gear throughout leveling and then buy the 70 gear when you get there. It also matters if you are fury arms or protection on whether or not you should get new gear as you go along. As a protection warrior you should be able tO edge them down and not get hurt inthat gear... Otherwise I would abandon it altogether. Leveling or battlegrounds for low level= more stats; better success rate