First off ... Welcome to EDH
Mono-white is often regarded as the best mono-color for EDH. It has answers to almost everything. AND it has great threats, which will make your opponents need answers.
The official Commander rules are that your commander must be a legendary CREATURE. Planeswalkers are not allowed, except for the few that specifically have rules text stating that they can be. If your playgroup allows it, then great. But don't expect to be able to take this deck outside of your playgroup and expect it to be allowed. I would suggest having a legal option ready so that you can swap it out.
You deck looks very good. Although I'm not sure what the strategy is behind
Gideon Jura being your commander. So I'm not really going to critique specific card selection at this point.
The biggest suggestion I would have for you is that you need some more mana ramp. I only counted five, and one of them is
Caged Sun, which costs 6 mana. I would suggest at least 4 more. Maybe even as many as 12 total non-land mana sources. There are things like
Land Tax or
Gift of Estates, things like
Pearl Medallion or
Thran Dynamo, and things like
Armillary Sphere and
Wayfarer's Bauble.
Solemn Simulacrum is a favorite too.
Your total land count is about right. Mono-white does like a lot of
plains, as most things only fetch basics. But one of your ramp spells is
Weathered Wayfarer. He can get ANY land. Feel free to add a few more non-basics. I run
Myriad Landscape and
Temple of the False God in just about every mono deck that I build.
Arcane Lighthouse will let you Swords a hexproof thing. I usually run at least one of the cycling lands (
Secluded Steppe) in a mono deck; sometimes more.
Hope this helps.
Happy Brewing