At this point you have nothing to worry about. He's 3.
At 3 he should start recognizing the first letter of his name. At this age, he might be able to sing the ABC song but he doesn't get the "meaning" of the song. Ask him what letter comes after k and you'll probably get some blend of lmnop - to him just a song, not individual letters.
It is also completely developmentally appropriate for him to be reversing his letters (it is developmentally appropriate until 2nd grade!) They will not test for dyslexia until the second half of the year of 1st grade. I would also guess that since he doesn't know his ABCs he has no idea which way the letters should be facing.
If you want to help him get ahead you can work on letters with him but don't push too hard - he's 3. I would also suggest working on rhyming - that can be a hard concept for some kids and it will actually help him when he starts to read in kindergarten. Say the word "dog" and start saying other words that rhyme with it. He'll chime in once he understands what's going on. Another tip - read to him, a lot. Ask questions about the story - "why did he do that?", "what do you think is going to happen?", "was that the right thing to do?"
If you're looking for TV shows - try WordWorld, Sesame Street, Super Why, Blues Clues.
Your son doesn't need "outside help". He sounds like a normal 3 year old. If you expect more out of him, you'll end up with a frustrated kid. Once he gets to kindergarten, whether he knows what each letter looks like isn't a big deal - they'll be going over ever letter because not all kids will know what they look like!