One possibility is that the mobs are having enough time to activate their damage shields. Watch for a force-field like effect, it can have a very large impact on the amount of damage that you do.

There's also an option in Preferences to auto target the closest enemy when you push an attack power button. I find in helpful when I'm in a heated close range fight. Also, don't forget to hit tab to target the next enemy. I bind "shift+tab" to "closest enemy" for when there are lots of things on the screen and I've accidentally targeted something across the room.

They are one shot missions that give very good rewards. If you have the credits to spare it's normally worth running them.

No, the only way to loose any recipes is to unlearn the entire skill. Some recipes may be one use only, but I'm not sure if there are any in this game. As an extra piece of advice, if you look at the color of the dot next to each recipe it will tell you how likely you are to gain skill in that crafting ability by making it. Greyed out items can still be crafted, but will give you no points.

I can't answer your second question, but diplomacy missions will give you light/dark side points.

Also, search is turned off right now, you didn't miss it. They'll bring it back when things calm down a bit.

Also, try to have 48k credits saved up for your speeder by level 25. It sounds like a lot, but if you don't go nuts buying things and do your space daily missions it's very doable.

Same issue, bugged it and got a reply that it was a known issue. No word on any fix though, so looks like we're stuck with a strange number for a bit.

Took mine about 30 min to show up, they come as one email.