Hey thunderring,

Basically record your dreams as much as possible, eventually you will find that you are writing longer entries. If a dream escapes you one night, don't worry, it happens to all of us. Just be persistent in your dream journaling and you will build up your recall

If the dream has disappeared, just try to remember, if you cant. Leave it and write in your dream journal "cannot remember" or something.
No its not a problem if you can't remember, it happens to everybody sometimes.
yes, the more you journal the more your recall will increase.
Well, try to record your dreams from naps, but... If you dont want to, dont worry.

Hope this helped.