1. Doesn't hurt to be on the latest baseband and bootloader. Some have better luck with different basebands so that may end up being some trial and error based on your location.
2. Battery reset won't hurt either and would give you a clean slate to start from.
3. Rom wise, if you want 4.3 you can't go wrong with slimrom. If you want 4.4 CMetal has the game right now.
4. Kernel wise, everyone has their favorite but Mpokang Kernel v10 is been making the rounds as fast with plenty of available ram. Since we only have a gig ram having plenty extra so there is less swapping helps.
If you are going to use a 4.4 rom make sure to grab the latest recoveries.