The two previous tenants damaged our property and stole things from our property and failed to disclose this to us. 

Fannie and Freddie DO NOT allow the transfer ~ you have to apply and be approved to do this.You apply to your servicer and either GSE to get approval of your SINGLE OWNER LLC and you have to disclose every little detail which takes away the reason people want to vest in LLC (to avoid personal liability).

So I'm a bit confused on this 1, it seems that its about disclosing the contractors used, not excluding owner builder.

Is it also the sellers' agent's fault for not disclosing this information even though she knew?

Unless we note otherwise in the listing information or disclosures, we fix everything that is broken or not functioning properly, but we have had several recent requests that are expensive and I'm interested in your experience in handling things like:- this roof is old and we're worried that we may have to replace it (was inspected by roofer and determined to be functioning properly)- there are screens missing from some of the windows and we would like you to add them- we're concerned about the drainage and would like you to add gutters- the AC unit is old (age disclosed in disclosure docs, was tested by HVAC guy and running fine) So do you budget for this type of concession, do you "meet in the middle" or do something else?  

How much does FM have to disclose re: the property? 

I disclosed that information because I could have easily stopped looking for properties and used that as a valid excuse.

I will obviously disclose everything to the lender and make sure that my DTI still stands acceptable (and I have seen the HUD requirements to get a carry-back approved, and met them all). 

Are their structural or hidden problems with the property he/she has not disclosed?

Disclose, disclose, disclose, as they say.