Etymological riddles

Two rather difficult riddles involving Polish words:

(1) Short as it is, the Polish word stryj [str+j] 'paternal uncle' ([+] stands for an unrounded high central vowel) is very likely related to BOTH *pxte:r 'father' AND *xauxos 'grandfather'. Can anyone suggest how they could be linked?

If it's any help at all, 'maternal uncle' is wuj [vuj] in Polish; as for the origin of Polish vowels, y < *u: and u < *au/*ou (thus also in most other Slavic languages, including OCS).

(2) Polish deszcz 'rain' (pronounced [deStS] = "deshch") is cognate to Russian doZd' and OCS dUZdI (Z = "zh"). What do these words have in common with English Tuesday?

Piotr