Jesus was born on this Feast. He tabernacled with man - in flesh. He wasn't born in December.
His life fulfilled the feasts on their exact day with just those future tense to go. But you can celebrate in December if you like, because He was conceived then.
No, the New Jerusalem is not here during the Millenial reign. Not till after the last rebellion.
No animal sacrifices during the Millenial reign. 'The Lamb' will be on the throne at that time.
There are other sacrifices besides just animal.
We're living sacrifices, or should be.
No, if you understand WHO and what these feasts represent, there is no problem joining those who take part in them. Could be a good time of witness and appreciation that our Bible is truly One book.
The first Church kept them, though we don't have to. Jesus was killed for Passover.
Not on the Friday before "Easter" (Astartes).
Hoy Vey. Ha.
The New Jerusalem is something that few really look into. Right now it's in Heaven, the "place being prepared for us". Our permenent address after the millenial reign.
But right now ... Heb 12:22 But ye are come unto mount Zion, and unto the city of the living God, the heavenly Jerusalem, and to an innumerable company of angels,
Heb 12:23 To the general assembly and church of the firstborn, which are written in heaven, and to God the Judge of all, and to the spirits of just men made perfect,
Heb 12:24 And to Jesus the mediator of the new covenant, and to the blood of sprinkling, that speaketh better things than that of Abel.
Gal 4:24 Which things are an allegory: for these are the two covenants; the one from the mount Sinai, which engendereth to bondage, which is Hagar.
Gal 4:25 For this Hagar is mount Sinai in Arabia, and answereth to Jerusalem which now is, and is in bondage with her children.
Gal 4:26 But Jerusalem which is above is free, which is the mother of us all.
Gal 4:27 For it is written, Rejoice, thou barren that bearest not; break forth and cry, thou that travailest not; for the desolate hath many more children than she which hath a husband.
Gal 4:28 Now we, brethren, as Isaac was, are the children of promise.
Making of the two one, gentile and jew is a beneficial to both experience ... the "law" we were freed from, did not necessitate that we can't respect the Feasts as Jesus did and does, by fulfilling them, as they all point to Him.
His whole timetable for His Coming, His work, His gifts poured out and His Return center on those same Feast Days, that He's never thrown out but will continue to fulfill on the days they fall on officially.
If they're His, I wouldn't mind attending more with folks. I've done Passover with my family ... knowing what the Messianic fulfilment was.
I think studying the Symbolism of the Feasts and seeing those He's fulfilled thus far and those yet to come is beautiful. It is all about HIM and HE's the One who made them ... and is fulfilling them each, one by one. Neat!