Firstly I'm no expert, I'm still finding out about all this, just i know now i would do things in a more disciplined and planned fashion next time.
With regard to 'who' to send it to, you need to research carefully, use the net.
What i did is to search the net to find independent artists who work in the same genre. After all there's no point in sending my singer songwriter rock ballad type stuff to dance/techno/house/rap people!
From these identified sites i looked at where they had got reviewed and where they had obtained airplay. Then I visited those sites and looked under the contacts,help, or FAQ page. Here it will usualy state their reviews policy (how they like to recieve stuff and so on).
If you can't find this after very careful searching (sometimes it's not easy to spot, look right down at the bottom of the home page for a very small 'contact' link for example), then email them a polite note asking if you could please send them something, etc. and asking for a name and postal address. Keep it short.
These days I refer them to my website in case they have a few minutes to look, but you have to be confident that your site will sell you and not be counter productive.
Often by this means you'll get back the name of an individual, which is good.
I think a hit rate of about 20% is considered to be fair, that is for every 100 albums you send out for review maybe 20 or so will get reviewed.
However, with more careful targetting it should be possible to improve on this. That's where careful research comes in.
To explain, I sent copies out to major publications, even though i knew there was little to no chance of getting a review. My thinking was if you don't send a copy to 'Rolling Stone' then there's no chance at all of anyone there picking it up, whereas if you do send one there's a tiny freak chance that it might just find its way into the right hands. A bit like the lottery ticket thing, if you don't have a ticket you certainly won't win. In any case what does it cost? $3 maximum for a copy of the CD a letter, envelope, and stamp - worth a try in my book. Send a copy to Timeout, Rolling Stone, UNCUT, etc and then forget about it - have no expectations.
Of course I'm assuming you can afford to 'waste' all these copies and postage, if you're on a very tight budget you'll have to target especialy well and decide whaehter its worth sending copies to these large publications, it's your call.
Oh, the 'links' pages of websites was also a great source of places to send copies. You know how it is, one link leads to another...
Here's a good one to start with
http://www.indiepages.com/linkszines.html
As far as getting gigs goes I'm not really qualified. It's all a bit of a mystery to me. The clubs all seem to need you to guarantee to bring along a crowd, but I'm just starting out so how do i get a crowd without playing somewhere first, and I can't place somewhere because i don't have a crowd, chicken and egg scenario! But at our level if you want to sell CDs you need to gig IMO.
As far as broadcasting goes you are lucky in the USA becasue you have the netwrok of college stations who will play unsigned artists and bands. It's much more imited in the UK. Recently I've been concentrating on sending stuff to podcasters. The audiences are small but at least someone hears your music, which is the whole point isn't it.
Feel free to look at my site and visit some of the places where i got reviewed and airplay. Assuming your genre is compatible.
If you have specific questions email me.
Got to get back to work now!
