You appear to have looked at your 'Local Plan' - they will have a policy in respect of replacement buildings and maybe restrictions on percentage increases in footprint or height. You need to reference this in your submission.
If the plans change the access for vehicles to their site or impair parking or turning there will be reference to requirements in the Local Plan and if this is so, again reference in your submission if it breaches them. Visibility splays are a good starting point. If the site is currently in conflict with access requirements but they don't intend on changing to the detriment, then the planning officer will likely 'ignore' any objection on those grounds.
If there are any protected species that you know of nearby, then point this out and ask where the ecology mitigation report is.
In respect of being overlooked, you should request that any ground floor fenestration of a greater area should not be entertained and any 1st floor should not have windows overlooking your property.
Your parish or borough council may have restrictions on boundary heights, if they do it will probably be 2m, but that may only apply to boundaries to a public highway. Some councils have no restrictions.
The position of the public sewer would not normally be a planning issue, more to do with building control, but still mention that your neighbor's proposal would conflict with the guidance.
Your chances of getting an application for a replacement building refused are probably zero. You can however make life 'difficult', and the planners will be respectful of your loss of amenity. You can delay things by drip feeding your objections in. If there a drawing revisions or additional information added to the application, make comments about them if you have any to make. The Planning Department put a time restriction on the receipt of comments but in my experience have always allowed comments well after the expiry date. You can check that with the planning officer allocated to the application. You can also ask when the planning officer is going to visit the site and can he be available to listen to your concerns. I believe they can refuse, but it is unlikely they will. Probably the best outcome for you will a scaling down of the building and a planning delay of a year or so. Falling out with your neighbors is likely, but it sounds like your not best pleased with them anyway.