What is the correct spare part for the counterweight system, what type of gas suspension or hydraulic piston does it have?

The Flycam Flowline 750N has the 750N Hydraulic Gas Spring.

Whether I can attach a gimbal such as Ronin SC 2 to this Flowline. If it needs other accessories to make that work

Yes, you can attach the Ronin SC 2 gimbal with the Flycam Flowline 750N but you need the Proaim handheld Star Ring P-STRG-01.

Height riser is compatible with 750N ?

The Flycam Height Riser for Flowline Body Support Rigs is not compatible with the Flycam Flowline Professiona Series 750N.

What happens if I exceed a 15 Kg camera rig ?

The Flycam Flowline 600N is compatible with 12-15kg weight only. For above 15kg, we would recommend buying the Flycam Flowline 750N. 

Can a flowline 600n work for a 16lbs rig?

Flycam Flowline 600N (FLCM-FLN-600N) has a load capacity of 12-19kg/ 26-42lb.
We have another model that is Flycam Flowline 300N (FLCM-FLN-300N) which has a load capacity of 5 - 8 kg/ 11 - 17.6 lb and will be compatible with the camera setup of 16lbs. Here is the link to FLCM-FLN-300N for your reference:
https://www.proaimusa.com/products/flycam-flowline-professional-ergonomic-camera-support?variant=22578867765333

Does this come with the shoulder rig ?

No, the shoulder rig is not included with this Flowline model.

Is this model ideal for gimbal and dslr or should i get something with heavier weight capacity ?

This Flowline comes with 2 different weight capacities as mentioned below :

What body sizes it will fit to?

It will fit to all body sizes from 28� to 56�.

Can I use cage with this flowline ?

Yes, you can use a cage with this flowline.

Can I purchase extra spring of higher strength to change and use heavier camera with it ?

Yes, you can buy extra springs of higher strength to use for heavier camera setup.

What is the weight of the Flowline ?

The Flycam Flowline itself weighs 4kg.

For how long can I use it continuously ?

This Flycam Flowline system can be used for whole day without any fatigue.

Can I use the Flowline placid arm with this Flycam flowline ?

Yes, you can use the Flowline placid arm with this Flycam flowline model.

Will this work with my easyrig model?

Yes, this will work with your easyrig model. You just need to drill a hole for mounting the placid arm onto your rig.

Does it come in bag packing ?

Yes, this Flycam Flowline comes in a bag packing for easy transportation.

Is it returnable for a full refund if it doesn't meet my expectations upon delivery ?

Yes, absolutely. We always backup our sales. In case, you don't like the product, we take it back within 30 days and you get a 100% refund.

What is the warranty ?

We provide 1 year warranty from the date of purchase. Items which are covered by the warranty period will be replaced at no cost to the customer. Replacement parts of the product will be provided at nominal cost (covering the cost price of the replacement parts only) to the customers after the Warranty Period has expired.