Front porch supports

I would suggest, Build brick/stone plinth, inset steel dowel, with new posts set on, prefably hardwood. Prop roof first, couple of acros. If roof isnt to big have you thought about having some gallow brackets made and fitted, you wont have any posts in the way then.

if possable and you can see how they our fixed to the roof. id replace them. you canrepair by cuting away the rotten timber and just replacing that. but in the long trem id replace the lot. unless your a good handy man id contact a carpenter to remove them. as surports will need to be in place before they our removed.

If they are rotting and split replacement is required..this can be done by supporting the roof with acrow props while you remove and replace.

we have done few of these like all others acro supports and replace with pressure treated timber or steel posts with wood treat all cut ends which you cannot get to when back in place or install on steel dowel and dpc

You could cut off the rotten bottom part of the posts and buid a couple of courses of brick at the bottom with a steel post support on the bottom of the post. ( can get from any decent fencing supplier) The type with flat fixing plate at the bottom to screw down on to your brick plynth. Treat the base of your post well after the cut of stage and as the post is now off the ground it will last much longer as long as it is treated properly. P.S. Do not forget to temporarily support the porch whilst working on the posts.