You can go to your local pet store and get some Fluval filter material. Most people give up on replacing filler material and just direct drip or buy some cartomizers.
The LR attys run hotter which develops more vapor, so you will be going through juice quicker. I wouldn't recommend using carts on an LR atty, just drip into the atty. You can also bet LR cartomizers.
Price is subjective. To some, $70 for a starter kit is a lot. To others, its no big deal. There are deals to be found out there. If someone wants to try out vaping, they sell disposable e-cigs that are inexpensive.
If liquid is getting down to the button area there are issues. Manual batts are supposed to be sealed. I would contact the seller and ask them for new batts.
Hey Bart, sorry to hear about your troubles but glad you're not giving up. As to your question, yes the 510 dual coil cartos will work on the eGo batt.