The Church did not have a dress code before V2, other than the issue of veils. Most of the issue of dress was cultural (society was more formal). The Church has not been in the business of dress code and most likely will not become so. On the other hand, issues of modesty should be addressed.
Church law has already addressed this: Communion on the tongue is the norm, and Communion in the hand is allowed at the choice of the recipent where permitted, and is what the Early Church did, and is supported by the Fathers of the Church.
A sermon is not proper; it is to be a homily. Having said that, the Church has a legitimate business in saying what a Catholic should do if they are true to the faith - not necessarily specifically, but certainly in general on major issues.
The Church specifically does not require tithings, as that is specific Mosaic Law; it requires that one support the Church. Tithing - literally 10% - is not required; for those who can do more, more than tithing is morally required; for those who can’t, it is most certainly not.
Already addressed by the rubrics of the Mass. Both are allowed by specific Church rule.
Both are allowed. Interestingly, what gets ignored is how many contemporary hymns are based on either the Old Testament or New - or both.
Specifically alowed by Church rules.
The issue came up in the mid 60’s; the Church has twice ignored the posture of the hands at the Our Father (two rewrites of the GIRM) and has ignored the issue in other realted documents where one would expect it to be addressed if it was an issue (e.g.RS). Rome doesn’t care. It is a non-issue with them.
Relates to a constant question asked long before Vatican 2 - “how much of the Mass can I miss and still fulfill my obligation?” Sadly, it shows a legalistic and minimalistic attitude about the Mass, instead of an attitude of joy and thankfulness that one can participate. Vatican 2 didn’t make too many inroads with the people who have the attitude; they have the same one their father and mothers, and grand fathers and grand mothers had before Vatican 2.
As to a dispute between the congregation and the pastor; if the congregation is demanding that certain things which are allowed be done away with, that is not their business.
And if the priest is requiring it, he needs to get in line with what Rome allows. Where there is a legitimate choice, teh choice can be made either way. Where one thing is allowed, it is neither the business of the priest or the congregation to insist that it is no allowed. e.g. Communion in the hand; it is allowed, and neither the priest nor the congregation has the right to insist that it not be allowed.
Songs are a choice; both are allowed. Choosing one of the other is fine.