the type of disc very much depends on what discs his player will accept. most dvd players will understand both 'plus' and 'minus' recordable dvds. reliable brand names include verbatim, maxell and memorex. supermarket own brand discs are a false economy.
i am not familiar with realplayer so cannot answer the second question, however if you find it not to be the case, look for a free version of a programme called nero, i expect they offer one on their own website. it is a user friendly (ish) and reliable programme for creating dvds, cds, etc. if they offer a free version, they will at every stage try to get you to upgrade to a premium ie expensive version but keep clicking on the buttons for the free one and eventually they'll give you it...
a conventional dvd holds 2 hours, so 24 x 5 minute clips. this is dependent on the video format you choose to use. the software will give you an idication of how much is going to fit on the disc before you commit to anything.
important to know, you must 'finalise' the disc for it to be playable in another machine. think of it as like making a cake - you can mix the ingredients but if you don't bake it in the oven, it's not a cake. again whatever programme you use it should guide you through this process.
good luck