Hello. For your first question I would recommend searching something like Terminal batch rename files. With a few lines in the command line you can very easily amend the page titles of a number of pages in one go. If you get stuck, just let me know and I can try to help - I had to do something similar.
For your second question I do not know I am afraid but I am not too sure if this is possible given the way each tool makes the links. Hopefully someone else that previously used Craft can help.
For anyone looking to do this conversion, I put together a script that can convert Craft documents and journal entries to logseq. Search for omair-inam/craft-to-logseq on github