Kmom- I'll go through each question 1 by 1, all the answers just IMO...
You can't really advise when to or not to showcase. I think its best to showcase no matter what, but people also have to take in their financial status and skill level honestly.
The biggest factors in picking a showcase I would say is to try to best pick out a handful of colleges, or maybe just a general area (Ie: the southeast) and choose a showcase from there. Most showcases listed on this site are accredited and very good, such as the TPX, college camps and the always trustworthy PG.
Narrowing down the college choices affects the decision of which showcase to attend greatly. With specific knowledge of his personal interests, a HS player can choose a showcase more directly centered toward what he wants. College camps are probably the best way to go in that respect, but check out some past posts on the site to see any state showcases and check the PG site, I know they run state and regional ones.
In terms of not narrowing it down, try to attend something that you feel would best fit your skill level. I don't recommend jumping right into, let's say, the PG National Underclass unless you've experienced a showcase before and know what you can handle. I know the Northeast showcases are high quality, but if someone is interested in the southeast like this forum has been directed, try Sunshine East or try to get to the WWBA champs. in GA, something like that.
***Don't forget, there are many other organizations other than Perfect Game that offer high-quality showcases (nothing against PG of course, have the world's respect for them). More specified showcases require some more research but are not hard to find***
If there is a specific school in mind, definitely attend that school's camp. That will get you the best one-on-one with the coaches and the most visability. But being a sophomore, don't assume that school is the be all and end all. Take Coach Merc's example, his son's dream school(s) changed, and whether it be for the better or the worse he was responsible enough to keep his options open and find a good home for the next four years (so the local papers say
).
As a soph., start out with an event that you feel is at your skill level. There's no need to feeling "blown away" at your first showcase.
~Josh