worried about my cats

my husband and I have 3 cats one VANS very loving mancoon age 4 (male) RORI  one large orange house cat age 6 (female) and GIZMO one smaller grey tabby age 1 1/2 (male). my cats are generally well behaved the only problem I have is with the grey tabby at times he will walk around meowing for long period of times and then will lash out on the other two cats or one of us.. although he is very loving he is much more affectionate with me. my concern is that I we are getting two new kittens this weekend and then Monday Gizmo has a vet appointment to be neutered. I'm very worried that the long term cats are going to feel unwanted also worried that gizmo is going to be very upset that he might think we are getting rid of him when I cage him and take him to a new vet. any thoughts or advice would be awesome

Gizmo's behaviors all sound like consequences of being an intact male! Within a few weeks after his neutering appointment, he should start feeling much more relaxed and happy when those hormones start leaving his system. For future reference, kittens can be neutered as young 4 months. This is a good time because it's before they reach reproductive age and start to get antsy, and younger, growing cats heal more quickly.

Gizmo will probably be a little confused and scared, depending on how comfortable he is with new people and places. You can spray his carrier with Feliway which might help. But soon he'll be given the anaesthetic and he'll go right to sleep, and when you pick him up he'll probably be too groggy to be very concerned. And then he'll be home again! Cats are pretty resilient, and will forgive you for a lot with time.

Cat introductions can be no big deal or very stressful depending on the cats involved, so just to be safe, it's best to take things gradually to help any anxious kitties get comfortable with the situation. These are good guides to follow to keep everyone as happy as possible when new kitties come home:
[article="32680"]How To Successfully Introduce Cats The Ultimate Guide  [/article][article="29726"]Introducing Cats To Cats  [/article]

I agree, and think the neutering will make the transition a lot easier. Is everyone else already fixed?