If you aren't doing so already, use knee braces or wrap your knees with an elastic bandage. Also ice the area 3 times a day for 15-20 minutes to reduce pain and inflammation.
You need to get the healers' attention or else you would never be able to kill Jad because they would keep healing him to full health. The key to handling Jad when the healers come out is not to panic. Your main priority should be to focus on the prayer switching. Once you switch to the prayer of the next attack, immediately attack one of the healers. Take your time getting the attention of the healers. Once u get all the healers off him, Jad is a piece of cake.
rarely anyone uses guthans because there are so many safe spots that u can range from. The only damage you will take on the waves to Jad are from the lvl 46s and 90s.
If you choose the p2p route, buying and alching ruby rings in zanaris would be your cheapest option. Factoring in the cost of the nature rune, you lose roughly 25gp per alch.
Godswords are slow and are only useful for their specs. Like Cat666 said, use a whip + rune defender unless u plan on doing a lot of GWD or PVP. As for making money, here are some options: 1. Green Dragons 2. Hunting Chins 3. Fishing lobsters
For the deposit box, you gotta start Rocking Out quest (up to the part where the guards tell you to deposit all your belongings into the box). As for yews, 80 is a good lvl to start.