freeze plug / coolant leak question 72 dart 318

ok found coolant leak this morning . 72 dart 318 . it is weeping from the back freeze plug passenger side top , at the firewall . i have never dealt with freeze plugs before . how do you get them in and out ? can i get this one out and new one in without taking the motor out ? from the top looks like a tight area to work with , but looks like from underneath , the trans filler tube is in the way a little . do these come out easily ? and maybe i can take off the oil filter to get more room to work . would changing freeze plugs likely fix the leak ? or , will i have to help seal it with something around the freeze plug ? also , what kind should i get and where from ? would one of those "HELP" ones from auto parts place be good enough ? what about silver seal / stop leak just to get by for awhile ? over 234,000 miles daily driver , so just trying to fix leak without pulling motor . any suggestions appreciated . thanks !