I'd say they are both Syngonium podophyllum cultivars, but not the same one. The top looks like the cultivar we (Aus) call "Spear Point" and the 2nd more like cultivar "ultra" though I'm sure there are plenty of "names" around. Also there can be a lot of change from juvenile leaves to more mature ones. Although you refer to one as a "water plant" indeed they will root from a node and grow in water, but will also root in well-drained but moist compost (like an orchid mix) and grow in soil. Either way they look for something to climb and the extra roots they make along the way both provide support and nourishment if they are lucky enough to find a suitable support - tree, porous wall, bark totem etc.

Dracaena deremensis "Janet Craig" most likely

Euphorbia grantii... Synadenium... African milk bush? Maybe if grown under lights... I'm used to seeing them outdoors.

The one he gave me look like that yellow pods but the heat level of the that pod was not as strong as Thai. He did have other pepper plants but I don't know if they are the same or not. I tried eating one yellow pod out of the plant a couple weeks ago but realize it was too young, no heat at all and the seeds were still translucent. Now I'm waiting to see if those yellow pods will eventually turn red or not.