I'm so sorry I forgot I was going to get the correct paths for you. I just got a new computer after two years of not being able to play and my excitement caused me to forget what I said I was going to do.
For skills
click sim, MC Comand Center, MC Cheats, Cheat Sim Info, Skills. From there you can choose what you want to do. Max all or select which skill you want to alter.
For relationships, you can either do this by clicking on the sim or from the relationship panel. Once you chose MC Command Center you click on Relationships then "Set Active Relationship Levels" from you can choose friendly or romantic and then select the type you want.
There is also another mod that will allow you to alter relationship levels just by right-clicking in the relationship panel. It will not add or remove relationships as MCCC can, but it is still handy to have. That is the UI extensions mod.