Yes, the heads on any cassette player does need to be cleaned periodically. You can purchase a cleaning cassette and solution that cleans the entire tape path. The cleaning kits are available at most retailers, and online.
No, portable cassette players do not skip.
Yes, there are dual portable cassette players.
Portable cassette players, commonly referred to as a walkman, was introduced July 1st, 1979. Portable cassette players were most popular in the 1980's and 1990's.
Yes most portable cassette players get radio and also record as well
Yes, there are portable cassette players with digital displays. Check online for the biggest selection.
Orange, portable cassette players are rare but they do have them. Try this site: http://www.videoavid.com/buy-electronics/p/Sony-WMFQ-1-O-Portable-Cassette.htm
Some portable cassette players are waterproof. The fully submersible Swimman works to ten feet and operates on 2 AA batteries.
Most cassette players nowadays supports playing dolby and records at the same time. This is one example -> O Coby O - Portable Am/Fm Cassette Player/Recorder or Sony Standard Portable Player/Cassette Recorder.
Yes, any standard set of headphones should plug into a portable cassette player.
Portable cassette players are often used by businessmen and secretaries in particular. However they're coming to be replaced by Digital voice recorders which don't require tapes.
Portable audio CD players have evolved in many ways. In fact, they evolved from bulky cassette players to walkmans (portable CD players) to what is most common now, Mp3 players that do not require a CD.
As a general rule, most portable players produced by Sony will not be able to play cassettes. This applies to current models and it is still possible to buy an out of production model which still has one.