Welcome to T.B.N. from Quebec!
Many options are presented to you. One thing we do not know, is how big is your average snow fall, and what yearly average?
If your Rino has a blower, then I would keep it for what good services it could render you.
As for the tractor tires, R4 and Lawn types make your tractor lower. Something to consider if going in the woods, or if there is a pile of snow in front of you...
Clearance is so important for winter snow clearing. Nothing worse than beeing stuck with packed snow under your vehicule
This said since you are planing for retirement...why not going with a cab??? Northern Alberta is a very cold place!! In the summer you just open the doors, or remove one, or both of them if you want. this way you can mount and dismount as quickly as on a open station.
If you plan on driving a lot on soft ground (like grass in the spring), R1 tires will quickly turn it to mud, I can assure you this! If you plan on going in the woods, then R1 will prove to be your best allie! Loaded tires and chains will make you life that much more relaxing, when times come to put your tractor to maximum use (pushing/pulling snow,stability and safety on icy slopes, etc).
Starting with a FEL, and the heaviest RB is to my opinion a good idea to get started with something well worth while. The RB should be as heavy as your tractor can pull.
The use of your tractor is not fully explained, but it seems your main goal is to do a garden, and some landscaping. Therefore, a machine with between 25 and 35 hp should be in the appropriate range.