[TexasSP]

On the doors, I would buy new. Hollow core doors are relatively cheap and you can get endless designs. Going from flat panel doors to ones like 6 panel or others with designs drastically improves the look of a house. You can get these made to about any height/width you need.

For the concrete I would saw and drill. You can get better saw blades to handle the rebar but half the time older houses used much thinner (say 1/8" diameter) wire versus rebar. Also, you nedd to make sure and dig around and replace the moisture barrier (if you have one) so excess water does not seep in through the concrete.