The paddle type keyer: Does it automatically set the length of time for the dots and
dashes, or are they simply two straight keys side-by-side?
Some basic definitions may help you:
A straight key (usually a single lever which moves up and down) is a key; a paddle (one or two levers moving from side to side) is also a key.
A paddle is commonly used to key (turn on and off) an electronic device called a "keyer" which, usually, produces dits and dahs automatically and weights (length of dit or dah) and spaces them appropriately for the speed at which the keyer is set.
Old, tube-type transmitters, in which a key would be turning on and off a significant amount of energy (voltage/current) often could produce noisy signals (key clicks, etc.). Such problems don't usually exist for contemporary transceivers whose keyed circuits involve very low energy levels.
A keying problem which CAN exist in contemporary solid-state transceivers is distortion of a keyed signal due to contact bounce in manual keys (straight keys, bugs, etc.). This is seldom a problem because of the near-universal use of built-in electronic keyers which do not respond to contact bounce in manual keys. Some contemporary solid-state transceivers, however, which, when keyed with a manual key, do exhibit problems with contact bounce. For these transceivers a simple debounce circuit can be used between the key and the key input in the transceiver.
Paddles, mechanical keys which are designed for use with electronic keyers, come in a couple of varieties: single levers and double levers. Both can be used similarly by pushing in one direction or the other to produce either dits or dahs. Single lever paddles can only be used in this way. Double lever paddles can be used alternatively by squeezing both levers simultaneously. The results of this squeezing depend on the type of keyer setup, for example, either iambic a or iambic b. Many keyer circuits allow selection of more than one type of keying.