I would like to create a website with a similar theme to clarity.fm. What is the best theme - especially for the Q&A and the Category?

You could probably use any Wordpress theme that had a design and feel you like. I would use a good events plugin such as Calendarize It. That plugin makes it easy to set up a nice calendar of events. You can make specific calendars for each country, category and city. They could view them all on one calendar or filter down to specific locations. You could even enter the venue information for the events as well. It's a pretty decent plugin. You can see an example of it working here: http://tvqma.org/schedule

It sounds like you just have a simple sales issue, and thankfully a high quality product :) The solution is simple, and you seem to have realized it already: you need to reduce the friction in your location for getting customers into your "front door" and providing them with (what I'm assuming) is a proposal. Also, feel free to use the word "agency" to describe your combined services. It's what we do :) So, my suggestion is to try reaching out to sales professionals in your area (Paris), and more importantly, with experience in your industry. You'll need to figure out how commission or payment will work, and then let them work their networked magic. Achieving sales leads is really just about your network. So if a sales person simply isn't within your budgetary reach, the next best thing you can do is just have every employee of your agency be their own salesperson. This means reaching out to colleagues from completely different industries, friends, successful people in business that you may have known from grade school, etc.... While sales seems like a crappy process at the start (yes, you are just asking for work from people), what you're building is long term, quality relationships with these people, especially if your final deliverables really wow the end client. From there, you'll find that your happiest clients will do most of the traditional 'sales' work for you :) Hope this helps! Feel free to give me a ring any time.

I've taken a quick look at your site and am happy to talk to you. Take a look at my reviews here on Clarity. Product advice is an area I provide a lot of help to Clarity members about.

Checkout is a high-quality WordPress theme by Array built for marketplaces of any kind. https://arraythemes.com/themes/checkout-wordpress-theme/ Let me know if you have any questions about implementation, and I'd be happy to setup a call.

*It Depends What are you trying to accomplish? You can do this with an email provider like MailChimp, AWebber, or Memberful, HubSpot. There are a number of WordPress plugins that work with your site if you are going to gate content for members or release content at certain times. I'm happy to help more, but I'd need a little more detail to give you an appropriate answer. Book a call and we can discuss more. All the best, -Shaun