1. Can an average joe still profit form mining LTC and ALT coins?
That depends on how much you can invest in your rig and how much you pay for electricity.
I believe that LTC was making around .0019 BTC per MH per day as of a few days ago. You should not expect to make much more then this. This comes out to be around $1.20 per MH per day.
2. Can you mine different ALT coins simultaneously... or do you have to mine 1 at a time?
SHA 256 coins (similar to BTC) can generally be merged mined with BTC. Most scrypt based coins need to be mined "one at a time"
3. When is LTC mining supposed to become too difficult or unprofitable? (ie-- are ASICS for LTC coming out soon?)
ASICs are in production as of now. The difficulty of LTC and other scrypt based coins will likely skyrocket in the next couple of months. Again profitability is based on your cost of electricity and how efficient your mining rig is.
4. How do you guys figure out the cost of electricity associated with mining?
You can look at your electric bill to see how much you pay per Kw/H. You can then use a Kill-a-watt meter to measure how much your mining rig uses.