In answer to question one: all I do is right mouse click and select save as, then put what ever descriptive name suits the pic.
In answer to question two: I have not used 98 since 2000. In XP you would click on My Computer / right mouse click on the C drive and select Properties / Disk Clean Up. After it done it's thing put a tick in what ever you want to delete...
Wombats do it in the dark.