@Alon A. I agree with the others and may suggest shopping it around, even working with a broker you should be able to obtain similar or lower fees and certainly better on the rate assuming there's nothing crazy for the property (doesn't sound like it is) and you don't have recent BKs, foreclosures, etc that would prohibit you from better pricing.
On the Refi - that's the easy part! Once rehab is done you can refinance and pull out up to 100% of the purchase price and rehab budget, not to exceed 75% of the new appraised value (ARV) in as little as 30 days from when you acquired it (if you did happen to complete it earlier than your timeline). To use your numbers for example, it would be the LESSER of the purchase price + Rehab ($355,000) and 75% the ARV ($450,000 x 0.75 = $337,500) soon as you complete the reno. No lease required yet and we could use appraisers 1007 market rent analysis.
Some lenders will cap you up to 80% of INITIAL cost, which would limit your loan amount to $284,000 ($355,000 Purchase + Rehab x 0.8). This is more common, just have to connect with the right lender!
Feel free to DM me if you'd like to chat more on that. 👍