I debated for a while about training him inside or outside too. My issue is that it's quite cold outside, so I didn't want him outside for too long. We ended up going with training him to go outside. We live in an apartment and built a box, put a pee pad in it, put it on our balcony, and have him go in there. He's getting the hang of it. He's only 4 months, but I've noticed amazing changes in the less than 2 months we've had him.
About crate training him - try to put him in the crate as much as you can while you are there, so he doesn't associate being in there with negative things, like you leaving. We put Hercules in his crate during the day and at night. The treat idea is good too. Also, slowly increase the amount of time you leave him in the crate. Hercules whines for a few minutes when we first put him in the crate, but it always ends. I haven't had too much of a problem with this.
Good luck!!
Brandi & Hercules