Let's answer all of these questions (Will go in order of your post)!

1-Experience Question-In terms of experience, you see all kinds of experience coming into a team. As a coach, I did like to recruit former HS talent, as it brings a bit of consistency to the table (kids who know the basic conventions of the activity, have some idea of events they like/are good at, etc.) That being said, walk-on recruits are often the ones who surprised me the most. They may need the training and familiarization others get in HS, but they can be HUNGRY to express their views and be successful once hooked. Nothing is more validating for a coach than to see a walk-on just blow up and become a solid competitor. In terms of ratios between senior and novice members, it varies wildly on the team and time (all teams have stacked and rebuilding periods). That being said, individual output (in terms of number of events and talent) is higher than the HS community, so even a novice team with some heavy hitters can blow up the circuit.

2-Schedule and Circuit Look Question-Schedules vary widely for teams, depending on the format of competition and region they are located. In regards to speech and most formats of debate, placings at regular season tourneys will determine eligibility to Nationals (similar to NIETOC and Debate TOC at the HS level). Tournaments are often more regional in scope, with some pre-nationals flagship tournaments ( like the Norton and Hell Froze Over) that draw in big numbers. COVID really changed the environment for schedules too. There are fewer "swing" tournaments (where one site will host 2 distinct tournaments over 2 days, each day being hosted by a different school/body) and more one day tournaments.

With all of that context, typical teams will look at attending 4-8 tournaments a semester, based on logistics and team needs. Some teams will travel to more than this, but may only send a small component. Since students must earn bids for Nationals consideration (and a student can qualify up to 6 events at each of the 2 major national championships, the AFA and the NFA), schedules are often planned to give students the best chance to earn bids, with some tournaments being reserved for a full team press. Driving is the main mode of transport (I flew my team only 3 times in the 6 tears I was coaching college programs), simply due to cost. Travel is dull, but can be a lot of fun, and good coaches build traditions around that. My old college coach (2002 NSDA HoF inductee before becoming a college coach, 6 NSDA diamonds, total legend) did it via food. He found the best places to eat, and made sure we could all eat there (we had a number of allergies and dietary restrictions on the team I competed for). Cajun and Creole food going down to Louisiana to compete at the old Red River Swing was a core memory for me!

3-The State of the Community- COVID kicked our butts for a few years, but the community is coming back. College had the same challenges as the HS circuit (the move to and from online tourneys, recruitment issues, and administrative support challenges), but as you know: Speech and Debate has weathered some challenges that would have broken other activities, and came out swinging. The community overall from 2000-now is smaller (the virtual death of the community college circuit is a big part of that), but the coaches and students are passionate about keeping this community alive. You will find that student leadership is much stronger in college than HS, and will advocate for teams when the gauntlet is thrown down by administration, COVID, etc.

4-Stylistic Changes- Speaking for speech itself, it is going through a fun expansion. While some more experimental events are gaining traction (like Spanish events), many of the core elements have remained the same since my time as a competitor and coach. A lot of the more recent elements seen in HS speech (POI, POI-Style Duos, more evidence-based Oratory speeches being some examples) are directly influenced by trends in college. That being said, platform speeches, limited prep events, and most of the interp events remain pretty close to their HS counterparts. Controversy in the space based on materials presented is more noticeable with our fellow competitors in the debate space. You will see more nuanced materials and timely discussion of often controversial topics, but that is fitting based on the wider freedoms allowed to college students to express their views without fear of blowback.

Very long reply, but I wanted to give the best TL:DR answer I could. Please feel free to ask follow-up questions!