Ask to move in or you can go to edit town and put them in the same house.
nope!
To become a business partner in the Sims 3, all you have to do is click on the place that you want to partner and click the interaction "Become Partner for $......." To become a partner costs A LOT of simoleons so make sure you have enough money to do so.
all you have to do is if you live with them make one relax on the bed then switch person and get them to join them if they dont live together get them to marry and they will move in together
You get access to more stuff.
You just need high speed internet to do a live stream on the SIMS 3.
Get to know them first, then do romantic interactions, and then ask them out.
You have to keep doing freindly and romantic interactions with the sim
Of course not! There is no diseases in the Sims 3, so they can live long lives.
A sim can be married to one sim, whilst dating another. But be careful you don't get caught, it can completely ruin a relationship.
No.
You need to become more romantic with your partner :D
If your partner lives in the house with you, simply select each sim and choose the relax button on the bed. If they do not live with you, select your sim and choose relax then click the other sim and select invite relax on bed.