Ok calm down a little please people are only offering their opinions (and concerns), you obviously care a lot for your piggies as you come on here and ask for advice which is good but you need to be willing to listen to peoples responses even if you do not necessarily agree with them.
My piggies have had little hats on their heads but I would never consider putting clothing on them as I know it would both stress and distress them and I would be doing it for my benefit and not theirs and the welfare of my piggies always comes first and I would hate to distress them in anyway I want them to be happy and content particularly as two are rescues and may not of had the best starts in their lives. Never the less caring for a piggy is a huge responsibility as you are responsible for every aspect of its welfare. I am very proud of the fact that I have three happy, contented and loved to bits piggies who are a huge part of my life. The first few weeks of being a piggy mum can be hard as you get to know your pigs, their likes and dislikes, their behaviour and so forth its also very tough for them as they are naturally timid creatures and they need to get to know you and their new surroundings and start to feel safe and happy in their new environment. I personally don't think trying to put clothing on them which will only serve to stress them will help this process at all, in fact it will hinder it.
As for putting leads on them, before I joined this forum I did have one piggy who I had a lead for at first she slipped out, when I got it to fit it felt incredibly cruel my 8stone against a 3lb piggy, when I tried to pull her back I felt I was hurting her and so I immediately stopped using it and binned it, I think they are very cruel and not good for the piggy concerned. If you want to retrieve a piggy rattle its food bag. Though they should always be closely supervised when they are out their cage.
As for Gerbil meeting piggies, why? It is going to be off no benefit to either animal as one can not offer companionship to the other and may well, as already stated for a number of reasons be dangerous to either piggy or gerbil or both.
Sorry if this has seemed like a lecture, it isn't intended that way.