Again, this time around pick yourself a much more survivable melee character. Skip the magic using until you become better as a player and learn to think more tactically (i.e. like your fellow player did with his becoming a kobold leader) or think outside the box with what your class can do with various skills.
As far as getting separated from your party, that's rule #1 in my book when I play, I never split from the party if I can help it. There is strength in numbers and one of the greatest generals in history said this little tidbit, "Divide and conquer." If you can do this to your enemies, you will win, if they do it to you, they win. It's pretty simple and it works to great effect.
Great DM's are not made overnight, it takes practice and it takes learning the ins and outs of playing. If you think you aren't very good, just continue playing and learning the game, when you are comfortable enough to give it a shot again, go for it. Some people are never comfortable enough to DM and rather play, that's a person preference and no one should ever be forced to DM if they rather play.
The bottom line here is just to have fun and enjoy the time you spend at the table with your friends.