Ok slings:
started with a stretchy or woven wrap.
I tended to use pashmina- type lengths of material as I just felt too damm hot in a long wrap.
You can lean forward, place the baby on your back, spread the material all over (including head) then tie so one side goes over your shoulder and one side goes round your middle under your arm. You may need some help doing this at first 
If you feel the head is too wobbly simply add another cloth around your back (African style) to pull it all in comfortably.
This is not the most glamourous option, but great for around the house.
I did cary both dts in a stretchy wrap at first on my front, but you're right, this is very heavy.
The main day to day way of carrying mine was to use a Patapum, though I'm sure other ssc are similar. You can start about now as they have a head support. They are BRILLIANT and you will be amazed at how quickly the baby gets into position on your back ready to be carried. You can of course carry them on your front in it, but maybe for your own sanity you need to work to sometimes carrying one on your back so you have hands free for the others.
For school runs I would sling one in the Patapum on my front or back, and the other in a pashmina on my hip.
I think that's all I have to say about slings covered- my other dc were 3 and 5 when dts born, and dh works away a lot, so putting one on my back was the only way to attend to every one and stay sane. Your situation sounds a bit more relaxed!