1. Yep. And PokeBeach as well.
2. Yep. That's a good sign.
3. Battle Frontier's already been confirmed for a while, and as it's the same as Platinum's Battle Tower's confirmed as well.

4. That was confirmed as confirmed could be as soon as HG/SS was announced, as there was no way they were taking that out.

/EDIT: Serebii overworld sprite=awesomeness(I'm gonna use the Japanese names I rememebr. >>

//EDIT: !!
Partners can be turned off =O Or maybe not, judging from Serebii's last post...
///EDIT: Clarification about the partner thing:
15:48; If you're in a small area and have a big Pokémon follow you, it will return to its ball
////EDIT: Silver has new default names.
If you're playing HeartGold, your rival's default name would be "Soul"
If you're playing SoulSilver, your rival's default name would be "Heart"
/////EDIT: DT: Yep, that's what I've been saying for months. =P
In unrelated news, I'm currently laughing at PokeBeach's coverage, as everytime they mention New Bark Town, they call it Littleroot town. =P