That all sounds good. Yes, just foliar feeding isn't going to be enough for a small tree through the warm months. Miracle Gro every second week would be good. As it gets bigger you're going to want to wean it to some slow-release citrus specific fertilizer.
All I can think of for the wilting is to keep it in the shade until you start to see some new growth, then gradually - very slowly! move it out towards more sunlight. Citrus trees really do need full sun to flower and make fruit. But that plant needs more roots before it can support its lush foliage in the sun.
