It is still a controversy whether ש after בגלל is proper form. My understanding is that, classically, it is bad form, but these days so many people talk like this that the structure is becoming socially acceptable.
Only ב כ ל merge with the definite article ה and take its ah sound.
The rule about how to pronounce “from”: “From” is usually mi but before gutturals א ה ח ע ר it may change to “meh” but even there if you say mi, you won’t sound strange to most Hebrew speakers. (YardenNB)