I know it's not a problem with the product, but rather my application of it. There's a few spots where I assume I applied the sealer a bit thicker so it looks more shiny in some places. I intend to screen sand the floor with 100 grit on a pole sander to knock down the raised grain, would this have any effect on evening out the sealer sheen issue?

I'm assuming the sealer's uneven sheen will carry through the 2 coats of Bona Traffic HD I plan on applying unless I address it? It's just a small rental, so I'm not hugely concerned of perfection, but it would be nice to get everything looking even.

The second coat of finish, or sealer will make the gloss level more even. The final coat will determine the gloss level.

Is it normal to do 2 coats of sealer? I had planned on 1 coat Bona Classicseal and 2 coats Bona Traffic HD. I'm just not sure if I should try and even out the uneven sheen with sealer or continue on to the polyurethane finish.

It sure won't hurt to use two seal coats and two finish coats. Scuff between coats with the pad, before vacuuming and tacking .

I'd rather stick with one coat of sealer if it's not going to cause a headache, just to save some time and money. I went ahead and sanded the sealer lightly with 100 grit screen on a pole, but it didn't seem to really do much except make the finish a little more dull. Does this sound like it was sanded enough? I did get a little bit of build up on the screen itself (a little).

I noticed that the sealer's instructions calls for "abrasion" if more than 48 hrs have passed. So, I'm a little worried that, since I have to wait a few days before applying my polyurethane coats, my pole sanding is not going to be enough abrasion and that I might get bonding issues. Should I rent one of those buffer machines to really sand the sealer well or should pole sanding suffice?

The pole sander should do the job. The first coat of finish will even out the shine and the final coat should make the finish an even satin sheen. I like to strain the finish to make sure that all of the satining agent is suspended, with no lumps, into an empty one gallon milk bottle with the top part cut off so the strainer will not fall into it while pouring the finish into the strainer. If the finish is not smooth, then apply another coat of finish. This will make it easier to clean the floor, and a little more of a wear layer.