Lion, excellent questions, which unfortunately don't have a black and white answer, nor a short answer.
None of the wires altE offers are tinned. Likewise, the cables coming off your solar panels also are not tinned. This is an age old dilemma for boaters, tinned wire is definitely best for boats, but no one I know of makes tinned wire with the solar connectors, and to correctly make them yourself requires a very expensive tool.
Most boaters we deal with in your situation buy the SMK pre-crimped wire like this, http://www.altestore.com/store/Cables-Wiring/Wiring-For-Solar-Panels/100-SMK-Connector-Cable-10-AWG/p10449/
twice as long as you need to go for your first connection and cut it in 2, one piece for plus and one for minus. For example, if you are using a combiner box, you would use this wire to the combiner box, and then provide your own tinned wire for the rest of the system.The advantage of using professionally crimped connectors vs tinned wire you crimp yourself is worth using a length of non-tinned wire for the outside connection that will be most exposed to the elements.
Unless you have other components that I don't know about that are MC4, I don't see any reason to convert over to MC4, just keep with SMK. Or are you wiring them in parallel with an MC4 coupler like this, http://www.altestore.com/store/Cables-Wiring/Wiring-For-Solar-Panels/MC2MC4-Branch-Coupler-1-Male-to-2-Female-Ends/p7163/?
If so, the answer to whether MC4 and SMK are compatible is also a little controversial. Yes they will work together, but some are concerned about long term connectivity, will they eventually not make a solid connection. I've got a foot in both camps for that one. Again, most people just connect them together with no problem. If you are concerned about it, you can use an adapter set like this, http://www.altestore.com/store/Cables-Wiring/Wiring-For-Solar-Panels/SMK-to-MC4-Array-Adapter-Set-MF-Pair/p10616/
Sorry, as I said, no short clear answer available. You can give us a call and we can discuss pros and cons with you to help you decide.
Solar Queen (and boater)