2) Even with Renault buying the team, 2016 will be a transition year, in which they can keep Maldonado's money and prepare for 2017 properly with money from Renault. Jolyon gets some experience and they ditch Maldonado and get a proper driver in order to return to the 2012/2014 form or even better.
Either way, Jolyon has to realize that he has to be the one that scores points for the team in 2016 - the other one will be busy screwing up the 2nd half of the grid.
I think it's probably this to be honest.
The wording of the Lotus announcement confirming Maldonado would be staying on wasn't exactly keen - "we signed a contract with him for 2 years, so yes he will be with us in 2016 (unfortunately)", so I think Lotus already knew they weren't going to have the ideal line-up they wanted in 2016 anyway.
In which case better to take the risk with Palmer during what is a transitional year anyway, use his extra money to bring more financial stability and hopefully development to the team and see how he gets on before the first "proper Renault" comes along in 2017 and they can choose the full driver line-up that they want.
Best case scenario - he'll be brilliant despite his lack of experience and really make the car perform, in which case they'll keep him on for 2017.
Worst case scenario - he doesn't quite live up to expectations, and while the car won't be good enough that he'll be losing them wins, he may lose enough points for them to replace him in 2017 when the team is more stable anyway.
Likely scenario - somewhere between the two. He'll gain experience and if they decide to keep him on they'll pair him up with a more experienced driver to help push him further (unless Maldonado displays a spectacular
comeback next year and they decide to keep both of them).