If you negotiate a provision in the Retained Life Estate contract for the right to lease the property for the remainder of your life estate, you can keep the additional money. You remain responsible for the taxes, insurance, and maintenance expenses spelled out in the agreement with the charity.
You are. Most likely the RLE contract will contain a provision that requires you to get prior approval from the charity to make such improvements.
Yes. The use of the asset is yours. Should you decide to lease for a while and then move back in, this gifting concept allows for that.
Yes. As long as the property qualifies under the IRS rules, it can be used to create this type of donation arrangement (i.e., you don't take depreciation or own it in a corporate structure, etc.) Check with your accountant to make sure it qualifies. Motor coaches and yachts qualify as second homes.