The video isn't nearly as important as audio. If you have great audio people will definitely sit through less than optimal video. People will not put up with crappy audio. A quality condenser mic is great. The Audio-Technica USB mics are awesome for the money and won't require a mixer to interface with them http://www.amazon.com/gp/product/B004QJREXM

For the love of all that is holy buy or make a pop filter for it. Otherwise make your script not use any words that start with P.

A mic that is much nicer but will cost a lot more and require a mixer is a Heil PR40 (lots of podcasters use these) http://www.amazon.com/Heil-Dynamic-Studio-Recording-Microphone/dp/B00PQYBRNY/ref=sr_1_1

A mixer is nice if you're going to do a live show but for a podcast it's not really necessary unless you are doing something simple like interfacing with multiple studo mics. Keep the setup simple and you'll use it more.

When you bring in remote people use Skype. Currently it has the best video/audio quality. Use a desktop for this with wired internet connection (or a solid 802.11ac wireless connection). No one like Skype connections that skip, jitter, and drop and as the host it's best to ensure those problems won't be on your end.

If you're doing video take set and lighting into account. Good LED lighting will make the biggest difference and make sure your set provides good contrast from the people and don't use "noisy" clothing. Remember you are making video that's compression friendly.

From the people I know who have done it they prefer to have local recordings done and after the fact they are sent to the host and mixed (best audio quality because you aren't using the Skype codecs), that can obviously be a hassle.

http://www.urbanismspeakeasy.com/blog/how-to-record-a-podcast-interview-using-skype/