For color you have two options<color:######> - Each # is a hex character (from 0-F) in the format RRGGBB where 000000 would be black, FFFFFF would be white, and FFAA00 would be a sort of orange.
Examples:<color:FFFF00>You're winner! => Yellow colored text saying you're winner
<color:00FF00>Succes => Green colored text
\c# - This is a control character you can place in strings with a # 0-8 corresponding each to a different color. You can find out the relation by typing /colortest in game. I also provided an image. So \c0 is red, \c2 is green, and \c6 is white. Notice these colors correspond to the default colors in blockland so if you need to match one of those colors exactly, you might want to use one of these.
Examples:\c0Blahblahblah => Red colored Blahblahblah
\c3Help me => Yellow colored Help me
For font:<font:NAME:SIZE> - The font tag allows you to specify the font name and size you want. The default font is Palatino Linotype (with the space) and size 24. Other commonly used fonts are Impact, Arial, and more (most fonts you see in a word processor like MSWord or open office are available in game.
Examples:<font:impact:20>Woah! => Uses the impact font and it's size 20. Looks boldish
<font:palatino linotype:24>Default can be fun too => Default font if you ever need to use if you've changed the font in a string and need to change it back for the rest of the string.
TML (torque markup language which is where the <tag>s come from) can do more things like images, links, text shadow, newlines, and more.
Hope that helps