Youll still gain points when you level and advance, and the only points you need to use to job advance is the ones you earned up to lv70, so no
Yeah, you will probably lose SP, because you must use all your skills points before advancing to the next class, otherwise you will not be able to advance.
You won't lose any SP. I've done it several times on my characters and I didn't lose any SP. You still gain +3 SP every level without the job advancement. Do your advancement whenever you want to, don't worry about it.
as i said you only have to use the ones earned up to lv70. All SP earned from 71 and onwards doesnt have to be used in order to advance to 3rd
