Trying to pronounce the letters correctly

I would like in shaa Allah to ask about things I face during my salah as every time I wonder if they break my salah or not. Allah created me in a way that it is a bit difficult for me to say letter R. In normal life its not obvious, no one even notices it, even me, but when it comes to say rrrrrrrrrr then I cant do that, which means Bismillehirrahmanirrahim is a bit difficult for me to say, I loose the sound of R if I am in my relaxed state. I have to give real efforts in order to pronounce it. My efforts don’t help much, R is still not so clear and I feel I only lose concentration in salah. Do I have to be making efforts or can be relaxed, how important is to pronounce R clearly? It’s the way Allah created me, can I be relaxed in my salah in shaa Allah? Other things that I experience during salah: last H in bismillehirrahmanirrrahim doesn’t come as soft as needed from my throat, because I loos air already saying all other letters in this words, so if it comes a bit harder then must be, if its close to the other Ha, is it something that voids my salah or requires sajda-sawh? In siratalmustaqim, letter Ta is difficult for me to say real hard, as to say R takes me to open my mouth and then its inconvenient for me to pronounce Ta hard as it must be. I should try to pronounce it correct but would like to know if mistake in this letter breaks salah? If saying D in gayrilmehDubi softer then it must be break salah? As above, in bismillehirrahmanirrahim, I cant stay long in double R, so I feel that I say double R, but sometimes feel I was to fast, is it ok or voiding salah? I noticed, when I try to say second double R properly, and then I have no air enough to say H in Rrahim soft as needed. In subhanerabbiyelA’le its hard for me to make a pausa in Ain as I was taught. Is any of these mistakes above break salah, require to read it again or require sajda-sawh, could you please let me know?