Unless he has been flying around for a few days already, he's not weaning. He's just experimenting and playing with food and learning to manipulate things in his beak. Keep offering it to him and make sure to introduce wet foods like sprouts and veggies. I don't know what lovebirds are like but some species are super hard to get eating veggies if they weaned onto only dry food. Once I start seeing interest in crumbled up dry food, I leave that scattered around on the floor but really start pushing the fresh and cooked veggies and sprouts and soak and cook mixes in a bowl. I try to make it so its wet foods that they initially really start eating and only after they've shown me they will eat a reasonable amount of that stuff do I start putting some dry food in their bowl a few times a day.
For the clumsiness, that should be mostly a maturity issue. Assuming he doesn't have splay leg or some other physical problem, he will just have to grow up a bit more. You can practice having him on your finger to give him something to grip. The little rope toys and the rim of a very low food bowl are good. For little birds, I usually get one of those squat little bowls they use to feed hamsters or reptiles out of from the pet store. That way they don't have to climb up onto anything or bend over much in order to get to the food or get used to eating it out of a container.
I don't move little birds into a cage until their first flight in most cases. Sometimes a little bit before if I just put them in the cage during the day and the brooder at night. They don't really get coordinated very well until they start flying so the wire cage bottom can give them some trouble. With larger species I usually have to put them in a cage before first flight because they start escaping out their brooder. I figure if they are able to climb up the high sides of the brooder then they can handle a cage at least during the day. If needed, you can put a towel over the wire cage bottom to make it easier to move. I would not put him in a cage until he's able to walk pretty smoothly, is fully feathered and seems to be doing a lot of flapping like he might be interested in flight.
