CR-V Guy

I recently purchased a 2002 CR-V out of state (rust free, factory sunroof) with just shy of 100k miles and I am going to pick it up next week. I haven't seen it in person yet, but after many phone calls, research and even hiring a mechanic to inspect it I felt comfortable purchasing it. The mechanic who inspected it said that he's not sure if the sunroof is closing all the way. I don't believe there is any evidence of water damage or else he would've reported it (I confess that I forgot to ask him, but he was hired to look over everything and based on his report he was pretty thorough). My main question to all of you is this: once I have it in my possession, how do I know if it's closed all the way? And, what do I need to do for routine maintenance? I've always heard that one needs to keep the drains clean, but is there anything else to do? Do I need to keep the seals lubricated with silicone so they don't dry out and shrink/crack? Should I periodically spray the mechanism with WD-40 to keep things free? Thanks in advance!