Say i have this configuration:

^{simulate this circuit – Schematic created using CircuitLab}

I want to calculate the Current going to the base of the NPN transistor. Specifically for PMBT3904,215 transistor, but I am trying to figure out a general rule for calculating the Ibase.

Because of the R2 and the 0.7V voltage drop of the NPN and the 1.2[V] drop of led, the current will be I=(5 - 0.7 - 1.2[V])/(100+400[Ω]) =6.2[mA] right?

I do not know if there will be any "surprises" for using the transistor on the high side.

Say I have this configuration:

^{simulate this circuit – Schematic created using CircuitLab}

I want to calculate the current going to the base of the NPN transistor. 

Specifically for PMBT3904,215 transistor, but I am trying to figure out a general rule for calculating the Ibase.

Because of R2 and the 0.7V voltage drop of the NPN and the 1.2V drop of the LED, the current will be I=(5 - 0.7 - 1.2V)/(100+400[Ω]) =6.2mA right?

I do not know if there will be any "surprises" for using the transistor on the high side.