Leaking Radiator 99 Galant

My stepdaughter's 99 Mitsubishi Galant has been losing coolant for the past week. She fills the overflow tank and it goes down after a few days, but the radiator is still full. We did have seeping from the top of the radiator several years ago and her dad applied water weld to the leak and this worked well for a long time. I noticed more seeping around the top so I applied the flex seal rubber coating. One pic of this repair is attached.

While I was looking at her air conditioning today, I noticed coolant dripping from the bottom of the radiator. I didn't see any leaks on the upper or lower radiator hose and I did observe a lot of coolant along the entire bottom of the radiator. I suspect the radiator is now beyond repair and needs to be replaced, but I surprised the coolant level is still full. One pic of the coolant at the bottom is attached for explanation.

I have these questions -

1st, is my diagnosis correct?
2nd, is the correct radiator for her car p/n MR312229 from RockAuto? Her car has the 4 cyl engine and VIN 4A3AA46G6XE115404
3rd, is this job fairly easy? I did find this link from youtube

http://www.youtube.com/watch?v=u7SAn0Ubq8A

Thanks for your help

its hard to fix the plastic and aluminum radiators, usually just best to replace them. can't tell from pics if it has a automatic with cooler lines or not but its usually not to hard to replace them. can also check e-bay for new ones, sometimes they are cheaper. just pic a seller with good rating

Hi Crvett69, yes, it has the auto cooling lines, tucked under the upper radiator hose (pic attached).

The youtube video suggested disconnecting these lines at this point and then removing them with the radiator. It should be easier to disconnect them from the radiator once the unit is out of the car.

The price at RockAuto is $70.79, I've asked them to confirm it is the correct part. I'll check eBay, but the RockAuto price seems reasonable.