1. You can use transient simulation but if that takes too long...envelope simulation can also be used
2. Usually the components/parts are categorised in @DS into blocks...e.g. System Mod/Demod, System PLL components etc...so i would say that you use ur intuition to guess which part will be in which block...i am unaware of any way of searching for components..from these blocks
3. Equations are very useful and can be both written on the schematic using different variable/pin names that you define. Also they can be written in the data display after you run your simulation(Post Processing). This is usually to do different operations (e.g. FFT, to observe magnitude and phase, etc) of the data which is produced after simulation....There are two help documents available in the @DS documentation each explaining writing equations on schematic and on data display...if you need them...plz let me know..
4.Unfortunately i dont have any idea wot TDA 7000 is...maybe you can elaborate it a bit more...
I hope my reply helps a bit..
Regards