In most cases a hydraulic car jack is strong enough, but you have to be very carefull working around it.

vwhippie, the corbels would make it too gingerbready IF you use gingerbready corbels. The door with its woodwork gives what is a very simple exterior the heft and interest it needs, esp. with those beautiful tall windows on the first floor. Adding somewhat simple, "farm-housey" corbels would beautifully carry the whole porch with what the door does and balance it out. As for the old house thing, never say never until the pro says it can't be done. As I said, there has to be an electrical box in that wall for the light you've got. An electrician can tell you if a pendant light can be wired to that box. If not, it can't. But the age of the house has nothing to do with this particular subject. As I said, my house is 1880. I just added an outdoor lamp because when I bought the house, there was a three-bay window in this wall that had rotted out, including the wall, and it made sense to put glass sliding doors in there, so I did. But it's needed an exterior lamp. I finally had an onion lamp installed a few weeks ago. It was a piece of cake. He just drilled a hole, and wired the lamp to the box that is in the wall. FYI: I was with a couple of kids, a 16 year old girl and 12 year old boy, and I showed them the pics, didn't say one word about who was proposing what. Showed them the pics, and then asked them which new light situation they thought was best. The girl I asked first (boy wasn't even around) and she said the pendant light. The boy actually said, "I"d put a light in the middle" as soon as I showed him just the photo of your front door and hadn't even shown him any of the mockups or even said anything about anything. So he also saw the pendant light right away. Genius kid! Lol.

What millworkman said: support the roof with a post or jack or temporary wall, then cut the bad post out. Use a post base on the replacements. On the top part, I'd just take a sawzall and slice between the beam and the 2x6s to cut whatever fasteners are holding them together. There might be a bolt cast into the concrete that the post fits over, so slice the post in half a couple feet up, then pull off/out the pieces. Once you get one out you'll know what you've got to work with on the rest, and you can just lather, rinse, repeat.

As usual, we concur completely with GN Builders. If you can have a local engineer look at it firsthand maybe they'll tell you it's fine? In the photo the wood doesn't look like it's rotted...., but more importantly that's a crack not a check! Based solely on the photograph and the fact that it is the only load bearing post.... prudence dictates to just replace it. A 4x4x10' #2 ground contact piece of PT will run you about $13.00 https://www.homedepot.com/p/4-in-x-4-in-x-10-ft-2-Ground-Contact-Pressure-Treated-Timber-288741/301913694 If you want to spend a little more money and upgrade to something that will probably outlast the concrete it is sitting in then............. https://www.soluslumber.com/product/ipe-4x4/