looks fine. I would generally try to account for pile placement tolerance. It is standard to accept 3" of placement tolerance so the layout should be designed for that - or what every tolerance value you specify.
No!!! Not really ...
Assuming rigid pile cap , linear force distribution is valid.
You are expected to find C.G. of piles then moment of inertia then find forces for each pile.
If all the piles similar ,
C.G distance form bottom line piles Ybar=3*1.2/5=0.72 m .
∑P (total compression load at three piles )=300*1.775/1.2=443 tons for each pile Pc=443/3=148 tons
∑T (total tension load at two piles )=300*0.575/1.2= 143 tons for each pile T=143/2=72 tons
The same result with using elastic stress calc.
Mxx=300* (0.575+0.48)=316 t-m
I xx= 3*048**2+2*072**2=1.728 m4
Pc=300/6 +316*0.48/1.728=148 tons
T= 300/6- 316*0.72/1.728=72 tons ( tension)
P.S.= This calculation is based on rigid pile cap approach and did not check if the hand calc. is correct. The design and detailing of the pile cap is a different story.
EDIT= I reviewed the calculation and the simplest approach is the use of equilibrium equations .
According to the grace of God which is given
unto me, as a wise masterbuilder, I have laid the foundation, and another buildeth thereon. . . .
I Corinthians 3:10