The blur on the reflectors looks correct to me, given that the reflector is travelling in a circular motion relative to the camera. The motion displayed by the leaves looks correct too as it is in the same plane as the bikes motion relative to the leaves.

I don't think the blur has been introduced in PP, I think it's a genuine image and not too difficult to achieve.

According to the annotation (place your mouse cursor over the bike) the camera was hand held and a VR lens was used.

It looks to me as if the camera was clamped to the cycle frame too.

It seems strange to me that you've asked several questions on these forums, to which you already knew the answer.

Can I ask, Why?

Rivals? What rivals? I don't have any, I'm a Pentax user.

If you already have a 70-300mm, surely a 17-70mm to go with it is a more versatile option. That would certainly be my choice.

It's difficult to determine what you were trying to achieve with these.

To me, they look no more than 'shots in the dark'.

#1 The problem here is that there is not enough light and/or too short an exposure. Cameras are light sensitive, without light, they do very little, as yours did in this case.

#2 The most interesting of them all, just. Had it escaped your notice that the horizon is not level?

#3 You'd need floodlights to light this scene, not a flash.

#4 Light bounced off the mist, but that's all.

Even when experimenting, it's good to have at least a subject. I don't see a subject in #1, #3, & #4.

... plus VAT

I'm happy to use my Rolls Royce cameras and lenses having paid Skoda prices.

I'm equally happy that there are other people happy to use their Skoda cameras & lenses who've paid Rolls Royce prices.

Yes, I know Skoda's aren't that cheap any more. I was looking at a Skoda Yeti today at a cost of €33,000.00

You're right, it won't.

Sorry, I didn't realise that the K-x has no shutter release socket.

Buy a pair of Cactus V5's and the appropriate shutter cable from Gadget Infinity.. 100 meter range.