Hi @Melissa_Hill , can you confirm how you reached this number? I tried recreating this limit in several ways and managed to hit the limit at only 100 tasks. So I’m curious… 
Regarding your issue, the closest workaround I can recommend is using Instagantt, which unfortunately just answers half of your brief; it is a timeline view, not a calendar and it currently does not retain your colour coding (but you can re-colour code within Instagantt as you please). Note it is free to use for up to 3 projects.
Alternatively, you could invite people to your Asana project as comment only members so they don’t have any Edit rights. If ‘No Asana login’ is an issue due to paying for more seats, you could add people to your Asana project as Guests instead. 
Below are some similar threads (which the @Forum-team could merge into one where we could all vote for this feature)
Marketing Calendar For Public Use
How do I make an Asana Calendar viewable to the public?
Sharing Calendar
Sharing (cleaned) Calendar view with non-Asana users
Sharing editorial calendar