I have a nephew who is 17 months and only just walking. He really doesn't talk much either. He can be noisy, but only has a couple of words. He's a second baby too. Their first walked late too (as did his dad), but was talking quite early.
I don't think the walking is an issue - in the long run it's not really going to matter when he walks. Apparently the average walking age is 13 months, so he's not that far off it.
With his talking, maybe look at how you interact with him. Because he's your second you might find you're not talking to him one-on-one like you did with your first. You might also not be encouraging him to use words, because you understand what he wants without him using words. If this is the case then you might have to try to remember to encourage him to talk rather than point, or grunt when he wants sonething (my SIL is currently trying this and thinks it's helping). I know that my first talks beautifully while my second has really bad pronounciation and no-one else can understand her. I know this is because we've not repeated words back to her and all that other stuff you do with the first. It's so easy to forget to do these things with the second child when it's not so exciting and you don;t have so much time and energy. When we crack down and ask her to talk clearly she can, but we have to stay on top of her. So maybe just have a look at how he's communicating with you and make sure you encourage him. I'm sure it's nothing to worry about yet though.
Also, I think boys are usually slower with their talking than girls.