Is this idea worth pursuing and if so, how do I validate it?

Try an infographic but if budget/skillset doesn't allow use a word doc and create a pdf. Whatever you do keep it short and sweet and a better suggestion is to use the body of an email for the actual pitch and the attachment/one pager or close too with supplemental info. No one likes reading and this is just an opener so they get a feel - you can answer detailed questions in a call/meeting

I think that Eventbrite is your best solution. It's simple to use from an organizer and user perspective, and there's little fuss in taking payments. No reason to get fancier.

When you say "2 platform app" are you referring to a multi-sided platform? or specifically a 2 sided marketplace? Like Uber that has a driver and a passenger? If this is the case I recommend you reading about multisided platforms — https://www.amazon.com.br/Matchmakers-New-Economics-Multisided-Platforms/dp/1633691721. Once you read it I will be glad to talk with you with this VIP link https://clarity.fm/mgalli/crack806-multisided but keep in mind I am not an expert, just a leaner too that can offer some little help.

If you have a wordpress site try one of these: http://premium.wpmudev.org/projects/category/plugins/?s=calendar

I work closely with an events agency in the UK, and have helped them manage the digital side of some massive events for clients like Samsung and Oracle. I'm also an official TEDx organizer, so I know a bit about the non-digital side as well. I've not come across many social media accounts or blogs that are platform-agnostic - The vast majority out there are product related and are always seeking to push the agenda and worldview of that particular product, business, agency or organization. Considering that at this stage, I know nothing about the size of your event(s), the potential audience, your admissions/attendee model and ideal target income for your sponsorship budget - My advice to you would be to research events agencies in your local area, or in your audience space, that could help/advise you. Here is the approach I would use: 1) Start small. In the events space, even small agencies can pack a big punch, and they are usually friendlier and more flexible. 2) Ask them for advice. If you're serious about organizing an event, they should be biting your hand off to advise you on what to do, and what to charge. 3) Offer them whatever you can to get the to buy-in. They might halve or waive their fees entirely if you can offer them an opportunity to speak, present or sponsor themselves. 4) Do a beauty parade. No matter how much you like an agency, always talk to more than one when you are planning and researching. You need to compare like for like. 5) Seek independent guidance. If you're new to the events space, then you run the risk of being taken advantage of. Once you have some options on the table, and you are looking at making a decision, run it past an independent advisor (like me) to get validation of what is being discussed. I'd be happy to discuss this with you on a call, if that would be of benefit - I have a few more negotiating tactics up my sleeve that may prove useful.