I teach 4 year olds and really, developmental milestones are reached by different children at different times. I wouldn't worry about it too much as some kids take an entire academic year to get those shapes down (especially the square and the rectangle.) I have even have kids go an entire year and still don't have any name recognition.
If you want to help him out, play games with him instead of sitting down to "homework time" Play games such as "I spy" (I spy a wheel, it looks like a circle, I spy a door, it looks like a rectangle) And trust me, most 4 year olds don't have the shapes and colors down perfectly. The fact that you are working with him will give him an advantage. Is he already in preschool? Usually going to school boosts children's desire to pick up this information because teachers do these things in a sing song way, and well, the competition helps.
If you want to start activities and sing songs, go to the web...websites such as http://www.atozkidsstuff.com and http://www.toddlertoddler.com/ might be of use to you.
Just remember, don't stress or make it seem like it is a huge deal that he can't do it yet, give him time, if he feels like he is dissappointing you, it may create a block and he will lose confidence in himself. As for his speech problems, it depends on where you live, really, but once he is in school you may want to ask and see where you can get information about speech therapy. In the district I work for, children with speech impediments receive additional support at no extra cost to the parents. See what your school district has available for you. Good Luck!