Trentlad I suggest you read up on what words means what and try learn first before starting to touch any application > phone live.
No. MyWi5.0 is the most popular but is $20 for the year.
This is pretty out of date.
I use TetherMe, which just enables the iPhone's stock hotspot/tethering feature without you having to have a tethering package. It doesn't have the advanced features of MyWi, but it does the job and it's only a couple of quid.
Or go to Cydia > Featured and get the Top apps for that.
Try deleting them and reinstalling them maybe? I had trouble updating Google Earth recently and that fixed it, but can't remember if it was pre or post jailbreak.