Yes, you can combine them just fine (though not on the same tile...). I can't what you're doing, based on on what you wrote, but to make tracks work you need the following (carved track for comparison):
Carved non-ramp track
*You need to set the connections of the track, which you do by telling the game which tiles a particular track tile can connect to. For a corner this means designating twice -- once from the corner tile to its entry side, and once from the corner to its exit side (entry and exit being relative).
Carved ramp track
*Again, you need to tell the game which other tiles each track tile is connected to, and again this means designating a tile twice if it's a corner. The difference here is that these tracks cross levels, but that doesn't really matter for the purposes of tile connections -- a flat track running in a line from east-west needs to have all EW tiles on the middle parts of the track, and a sloped track running from east-west also needs to have all EW tiles. (This isn't actually true, since a ramp running downwards from east to west can be guided in either direction when all the track tiles are W only.*) You can't designate it all in one go, unlike straight track, as track designations don't carry through z-levels.
Constructed non-ramp track
*For straight sections this works something like carved track. You select EW or NS, increase the width or length of the tile area as necessary, and place it in sections of one to ten tiles, or more if you're making parallel tracks. For corners you need to place the tiles one at a time, and select the connection type from the list.
Constructed ramp track
*These always need to be placed one at a time, and you need to select the connection type from the list. As with carved track, the change in z-levels between tiles has no effect on the connection type needed.
You don't need to construct ramps on open space. As with regular constructed ramps, they're only created as up-ramps and the game fills in the down-ramp on the level above. You should be able to construct a ramp while the dwarf is standing on the site -- I've done it before.
* I believe you'd need the proper connections if you wanted to use power to get the cart up the ramp. I'm not sure what's going on with the track connections in that case -- I think the dwarves are shoving the minecart along the ground because there is no track running between stops, but because all the ground tiles they're shoving the cart across are track tiles those tiles are creating the amount of friction appropriate to a fully-functioning track. But I don't know that for sure.