I figured its good to have a couple individual ships ready for the defense of the sol system incase i dont have a whole fleet ready for expeditionary deployment. 
This ship was made using nuclear pulse technology, i think that is considered tech level 2 and not 3 as far as i can tell? Is it then in most cases better to hold off on building any tech level 2 ships and design a whole fleet to deploy at tech level 3 instead? Unless i come under attack beforehand i suppose. 

When designing, you should consider the overall design of your fleet before you design individual ships. For example, you might design an escort that will never be deployed alone, so it doesn't need long-range sensors. Or you might design a large missile warship with no point defence, because it will never go anywhere without escorts. Will you have tankers along, or do your ships need to operate at long distances without logistic support. Do you need fast ships, or just a type of fast ship within your fleet mix that can handle certain situations. When you consider fleet composition, you don't necessarily need a ship that can do everything, or deal with any situation.

No smeg? Well that's interesting for sure.

I have landed ground forces on an enemy planet and the sensors are active, yet I cannot see how many tons of enemies are left. Why is that?

What is your sensor resolution? Usually you need a RES-1 sensor to detect ground units in my experience.

Since i mainly don't want to be defenseless even though i don't know what i'm up against yet i decided to go with aforementioned much lower range but much smaller/faster vessel. 
For now i will drop the beams until i can design a more fit for purpose ship with them.   I haven't been able to come up with a good two stage missile yet but i have redesigned my old missiles to be shorter range but a decent amount faster. 
I'm confident that if i score a hit or two they should do good damage but will my volley size be large enough to penetrate the kind of missile defenses i can expect from raiders if i group a couple of these in a fleet?
Is going with a single engine just too risky as a rule of thumb or is it more of a personal choice?

Kvikk class Missile Boat      6,000 tons       167 Crew       856.9 BP       TCS 120    TH 480    EM 0
4000 km/s      Armour 3-29       Shields 0-0       HTK 52      Sensors 0/0/0/0      DCR 1-1      PPV 24
Maint Life 1.42 Years     MSP 589    AFR 288%    IFR 4.0%    1YR 320    5YR 4,797    Max Repair 240 MSP
Magazine 272 / 0   
Captain    Control Rating 1   BRG   
Intended Deployment Time: 24 months    Morale Check Required   

Orobos Turbines NPE-EP480M (1)    Power 480    Fuel Use 110.23%    Signature 480    Explosion 15%
Fuel Capacity 263,000 Litres    Range 7.2 billion km (20 days at full power)

Temetor Ordnance S6ML (4)     Missile Size: 6    Rate of Fire 25
Temetor Ordnance MFC49-R20S (1)     Range 49m km    Resolution 20
Temetor Ordnance ASM6 Mk2 (45)    Speed: 19,200 km/s    End: 4.1m     Range: 4.7m km    WH: 9.00    Size: 6.00    TH: 64/38/19

Vivar Warning & Control AS52K-R50 (1)     GPS 4000     Range 52.6m km    Resolution 50

Missile to hit chances are vs targets moving at 3000 km/s, 5000 km/s and 10,000 km/s

This design is classed as a Military Vessel for maintenance purposes
This design is classed as a Warship for auto-assignment purposes
PS.  These are mostly tech 3 components i think (or is nuclear pulse and equivalent techs considered tech 2?)