Oh, now you're posting in the correct forum, eh?
1. Yes, for counterspelling. However, if you have a mage, your mage will take care of the counterspelling task of identifying the incoming spell.
2. Yes, it is a nice feat. I use it myself.
3. Especially for mages. Run away! Run away!
4. Spell penetration. Combat casting. Anything that improves concentration. Spell focus if one of those areas is a main area for you (like enchantment). There are four elemental focuses too. Each gives you a 5/- resistance to the elemental damage and makes your elemental damage spells better. Also, work on your missile weapons. There will be times that you will be down to missiles.
5. Intimidate. Wilderness lore. That's about it.
6. I play Lathander, Ilmater, Mask, Selune. Maybe one or two others. I experiment a lot.
7. I don't use a full-time rogue. I multi-class a woodelf (sorcerer) or teifling (mage) or female drow (cleric) or gnome (illusionist) half-elf/human/dwarf (fighter).