There is a difference between compatible and remanufactured cartridges. Compatible cartridges are more likely to have problems as they are more prone to being a bad fit due to the manufacturing process.
Remanufactured cartridges are original cartridges which are recycled and refilled...
I would not recommend adding toner into your cartridge, instead I would just buy a remanufactured toner cartridge. I have bought from newegg.com and sonictoner.com in the past and I have been happy with them. The quality is good and the prices are great.
I have used epson printers in the past and it has worked out very well for me, but the Epson printers dont seem as durable. I am now using a HP, but haven't printed pictures with it yet.
If you are able to take out the used cartridge, then you can tell. Like Lisa said, if its a long cartridge even down to 8" its probably laser. If the cartridge is palm sized its ink.