What is the difference between organosilyl, alkoxysilane and silane compounds?
Silane is the equivalent of methane for silicon, $\ce{SiH4}$. 
Silicon containing organic derivatives of many kinds exist.
Generally speaking, organosilanes are those in which $\ce{Si-C}$ bonds exist, like for example, tetramethylsilane ($\ce{TMS}$, used as a reference on $\ce{{}^{1}H~NMR}$).

Alkoxysilanes are those compounds that contains an organic group bonded to a silicon but not directly, through an oxygen atom instead, like so: $\ce{R-OSi(Me)3}$, common structure on silyl enol ethers.

A surface is hydrophobic if it's repulsions towards water overcome its attractions, and this is the case for many silicon compounds, but not all of them. For example, glass (silicon dioxide, $\ce{SiO2}$) is hydrophilic, due to the possibility of formation of hydrogen bonds between the glass oxygen and water molecules.