First off, Silverwood is my adopted home park and probably the park I've been to the most so I have a lot to say about it.
To address your questions:
1. I agree with Bottom_Feeder in that Tremors is not what I would call "intense". That's not to say it's not an amazing ride. I'm not really sure what to compare it to because I haven't been on my subterranean woodies, but it's definitely a unique ride.
2. I'm pretty tall, 6'5", so I guess any tunnel can feel questionable to me. But I have been on Tremors enough to know that it's fully safe, haha. The tunnels are definitely the defining aspect of the coaster and much of the reason that it is in my top 10 (also it has a high nostalgic value for me as it was one of my first coasters). Even though it was mentioned in the last post, the first tunnel is really great as it goes through the gift shop which also makes it fun to just chill in the gift shop when the train comes roaring through making the entire shop rattle.
3. I'm not really sure what to say about the airtime on Timber Terror. It's nothing extremely overwhelming but it's solid. The double up provides some nice ejector as far as I remember. Since it is an out-and-back layout, the main idea is airtime so in that sense, yeah, it's pretty good. Best seat for airtime is probably the back except for on the double up it might be somewhere further up the train, don't remember exactly. You will probably get a chance to ride wherever you want as much as you want.
4.The lats on Tremors are undoubtedly much better and I love the helices in the back of the layout. They can be quite forceful. I think Timber Terror had some good lats on the turnaround but probably not much with the helix. It really is more about airtime though.
5. Well, again since I'm fairly tall, Corkscrew has become painful for me but it is the first coaster with an inversion (as well as my first inversion on a coaster) so it's kinda a must-ride for historical reason, even if only that one time. There will be no wait for it and that is a guarantee.
As for my opinions of the rest of the park:
Silverwood is truly one of the cleanest parks I've been to, both in terms of the path and the overall looks of the park. The atmosphere is incomparable to anything else for me because of the memories I have there. I really like the theming everywhere (nothing too over the top) and I never get tired of the cheesy banjo music. I highly suggest the huckleberry funnel cakes! Don't miss out on them!
Aftershock is a very high quality ride and probably one of the shorter waits you will ever get for a GIB even at peak times. I did have an issue once with tweaking my back when I rode it but it's nothing to worry about and I didn't even care because I got caught up in the excitement of the rest of the day. All to say, don't miss Aftershock as it is quite a fun ride.
As for the other rides in the park, my favorites are the log flume, river rapids, paratrooper (I know, kinda random), and the drop tower is pretty fun too. The log flume is classic and a really nice relaxing ride with a decent drop. The line is often outrageous (especially compared to the rest of the park) but I usually ride it once anyway. The river rapids are great in my opinion and are the most consistent I have ever been on in terms of getting you totally soaked. It's pretty much a 99% chance you will be drenched when you step off it, plus it's all downhill which is great.
The water park is top notch in my opinion. Once again, extremely clean and very open feeling. The lazy river is awesome (as they don't force you to be in an inner tube) with a nice swift current in parts. And if you are of age, there is a bar literally in the water where you can buy drinks and take them with you down the river. Very unique and fun. The speed slides are the best I have been on and the tube slides are pretty quality too. They have added an addition family "raft" tube slide since I went bringing their total to two. I enjoyed the first a lot and I'm sure the new one is great too. The locker system is great and fairly cheap in my opinion. There are two wave pools (although I don't think it's necessary) and are definitely not a must-experience part of the park.
As a whole Silverwood has a ton to offer for not being a part of a chain and the cleanliness and friendliness of staff, etc. make it one of my favorite parks. I hope you really enjoy yourself and I'd love to hear about how your trip goes. Tell me how the new family tube ride is.
On random note, Silverwood is rumored to get a new coaster in 2013! I'm keeping my fingers crossed! :-D