yes and yes. you just have to know what you are doing. i'll give you a breif walkthough...
first, download audacity 1.2.6 dont use the 1.3.X versions, they are beta testing versions and are unstable.
click here: http://audacity.sourceforge.net/latest/audacity-win/audacity-win-1.2.6.exe
ok, now as for your phone, most phones today play mp3 files, some do waves and some use amr. audacity can export as wav and mp3. but to use mp3 you first need to have the lame 3.96.1 encoder for audacity found here: http://www.webhostxpress.net/~mitiok/lame-3.96.1.zip
extract that to a folder here you wont forget it. open audacity, open the audio project, click on edit>preferences>file formats>find library>open the lame_enc.dll file that you just extracted. to the left of the find library button is a drop down menu of the available bit rates for your mp3. the lower the number the worse the quality but the less space it uses. 128 is a good compromise of space and quality where 320 is "cd quality". click ok.
now, just import the sound clips you want to use, click on project>import audio>open the file you want. now you have the entire song/sound that is on the file. to "crop" it, just use the selection tool, (looks like an I) select what you dont want and press delete, you can use the arrow keys to do very slight adjustments, ctrl+1 or ctrl+mousewheel up = zoom in ctrl+3 or ctrl+mouswheel down = zoom out. once you have the clip edited to where you want it, make sure it is aligned with 0 seconds so your not listening to minutes of silence first, either use the tool that looks like an arrow point left and right to drag it, or you can click project>align tracks>align with zero. now that is done, all that is left is to export it.
click on file>export as mp3>pick a name to save it as and there you go.