I'm firmly of the opinion that the Sims community works best when things are shared freely, so I'll let you do just about anything you want with these objects. More specifically:
If you do share items based on these objects, you are not required to provide a link. However, I'd rather you didn't go claiming this as your own work. If you do want to provide a link, then either this site (http://www.eternal-echo.net/sims) or the related MTS2 thread would be fine.
You might want to read this first though, to save you some trouble:
Using in lots
If it makes sense to use my objects in a lot (ie - you're sharing a farm or a house with developed garden and you want to include crops,) then you may include these objects in a distributed lot with credit. I would prefer that lots created with the express purpose of mass distributing downloaded objects not include these. The former celebrates a creator's work, while the latter celebrates the redistributor. If you're not sure which category your lot falls into, then ask me directly - I'll most likely give permission .