Any propeller guards (10x4.5 props) for this frame (Q450)? Also is the landing gear is too big for this frame as it tips over in front or back while hard landing (am a newbie, not enough practice) any advice/ ideas fellow quadders?

The landing gear looks pretty tall .

Yes Santosh, that's what i felt too after fitting them, but the site said it was meant for this frame so i bought it, it's been raining here so have tried them only once. Thinking of going back to smiley balls i had put earlier if it keeps tipping over.

My suggestion would be to not use the Landing Skid at all for the time being.
The small landing skid on the frame arms is already good enough for beginners since it gives a wider contact to the ground. It's not easy for the props to touch the ground in this case. If in case you fly from the field, Just make sure that you fly from a surface with grass no higher than the arms.

Don't use the smiley balls either as it can induce some unwanted bumps when while landing.
Let it stay all stock. Just keep some spare props handy. You'll need them.

Also keep inspecting the hub of the props from time to time as at times with harsh landings, props tends to become a bit weak at the hub and then the same prop would break mid flight later on resulting in unnecessary damage to other props.

Thanks Bavesh, learnt the hard way by breaking a prop today morning, but I have a spare set, removing this landing gear today itself (this was my second flight with the new gear), will fly without any till I learn to land safely and slowly.

Yeah it's perfectly normal to break props in the beginning.
Just make sure that you do inspect the hub of all props from time to time. Specially after a crash.
And keep adequate amount of (balanced) props in stock for the time being.

The benefit of a multirotor (specially nylon frames) over a helicopter is that you hardly have anything else broken except the props.
So the repairs are way less costly and super quick.