I think if he's happy to go to sleep & stays asleep then he probably needs the sleep. If he is only 8w old then he'll still need quite a bit of sleep and a 2 & 1.5 hour sleep doesn't sound excessive to me. Waking 3 times a night at 8w old would be pretty normal too. My DS spent a lot of time sleeping in the HAB up until he was around 9-10 months I think. Sometimes it was the only way I could get him to have a day sleep and he would happily sleep for 2-3 hours in it.

As for only sleeping when you are standing - I'm thinking there could be a few reasons for this. Maybe he likes the slight rocking movement (after all bubs are rocked to sleep in the womb as mum walks around), in this case you could either stand until he's in a deep sleep, try sitting in chair and rocking/swaying, or try sitting on one of those gym/fit ball things and bounce gently on that. If you make sure he is in a deep sleep before you attempt to stay still then it may help, and if he starts to stir you can rock/bounce slightly to try to settle him. Also the position you are sitting in may make a difference. Kynan preferred it when I was sitting up straight, not leaning forward or slouched down in a chair.

HTH!