Error de compilación del sistema de alquiler de coches

Estoy escribiendo código para un sistema de alquiler de coches, pero recibo algunos mensajes de error de compilación que no entiendo.

El primer error es

TypeError: la expresión tiene que ser un lvalue.

el segundo es

TypeError: la dirección de tipo no se puede convertir implícitamente a la función de tipo esperada () ver devoluciones externas (dirección).

el tercero es

TypeError: Operador < no compatible con tipos uint256 y función () ver retornos externos (uint256).

Aquí está mi código:

TENGA EN CUENTA: El asterisco representa qué línea en los errores de código.

pragma solidity ^0.4.18;

contract rentCar {

    struct Renter {
        address  addr;
        uint DOB;
        uint currentRenting;
    }

    bool public rented;
    address public owner;
    uint public duration;
    uint public rentalPrice;
    uint public charge;
    uint public rentalDate;
    uint public returnDate;
    uint public rentalStartDate;
    uint public rentalEndDate;
    uint public constant totalDays = 7;


    struct NameKey{ // storage the name's keys
        uint[] keys;
    }

    //List of Cars available
    uint[] private ids;  //Use it to return the ids of Objects
    uint public numofCars;
    mapping(uint => Car) private cars;
    mapping(string => NameKey) private nameToKeys;

    //Events
    event E_addCar(uint objID, address VechileOwner);
    event E_Rent(address indexed _renter, uint _rentalDate, uint _returnDate, uint _rentalPrice);
    event E_ReturnRental(address indexed _renter, uint _returnDate);

    //Modifiers
    modifier onlyOwner() {
        require(msg.sender == owner);
        _;
    }
    /*
    modifier onlyRenter() {
        require(msg.sender == addr);
        _;
    }
    */
    modifier whenNotRented() {
        require(!rented);
        _;
    }

    modifier whenRented() {
        require(rented);
        _;
    }

    //Funcions

    function rentCar() public{
        owner = msg.sender;
    }

    function addCar(string make, string model, uint pricePerDay, uint minRentalDay, uint maxRentalDay, bool available) public onlyOwner {

        Car newCar = cars[numofCars];
        ///nameToKeys[name].keys.push(numofCars); //add the key to the name's keys
        ///***ERRORS
        newCar.VechileOwner = msg.sender;
        newCar.make = make;
        newCar.model = model;
        newCar.available = available;
        newCar.pricePerDay = pricePerDay;
        newCar.minRentalDay = minRentalDay;
        newCar.maxRentalDay = maxRentalDay;

        newCar(numofCars,msg.sender);
        ids.push(numofCars);
        numofCars++;

    }

    function setAvailable(uint objID, bool _available) public view onlyOwner {
        ///***ERRORS
        cars[objID].available = _available;
    }

    /* function totalDays (uint rentalStartDate, uint rentalEndDate) public whenNotRented{
        uint totalDays = ;
        return totalDays;
    }*/

    function Rent(uint objID,uint totalDays) public payable  whenNotRented returns(bool){
        ///***ERRORS
        require (msg.value < cars[objID].deposit);
        require(totalDays >= cars[objID].minRentalDay && totalDays <= cars[objID].maxRentalDay);


        cars[objID].renter = Renter({addr:msg.sender, currentRenting:now});

        uint PayDeposit = msg.value - cars[objID].deposit;
        rentalPrice = totalDays *  cars[objID].pricePerDay;
        rentalDate = rentalStartDate;
        returnDate = rentalEndDate;

        cars[objID].available = false;
        rented = true;

        // accessCar();

        ///***ERRORS
        E_Rent(Renter, rentalDate, returnDate, rentalPrice);

        return true;
    }

    function endRent (uint objID, uint duration) public  whenRented {
        ///***ERRORS
        duration = (now - cars[objID].renter.currentRenting) / (24*60*60*1.0);
        charge = duration * cars[objID].priceDaily - cars[objID].deposit;
        uint totalPayment = msg.value - charge;

        require(!cars[objID].VechileOwner.send(charge));
        require(!cars[objID].renter.addr.send(charge));

        delete cars[objID].renter;
        cars[objID].available = false;

        E_ReturnRental(Renter, now);

        resetRental();
    }

    function forceRentalEnd() public onlyOwner{
        require(now > returnDate && rented);

        E_ReturnRental(Renter, now);

        resetRental();
    }

    function resetRental() private{
        rented = false;
        Renter.addr = address(0);
        rentalDate = 0;
        returnDate = 0;
    }
}

Tengo un segundo contrato llamado Car que interactúa con el otro contrato

contract  Car is rentCar {
    address public VechileOwner;
    string public make;
    string public model;
    Renter public renter;

    bool public available;
    uint public pricePerDay;
    uint public deposit;
    uint public entrycode;
    uint public minRentalDay;
    uint public maxRentalDay;

    function checkAvailability() public view returns (bool) {
        return(Car.available);
    }

    function Car(string _make, string _model, uint _pricePerDay, uint _minRentalDay, uint _maxRentalDay, bool _available) public onlyOwner{
        make = _make;
        model = _model;
        pricePerDay = _pricePerDay;
        minRentalDay = _minRentalDay;
        maxRentalDay = _maxRentalDay;
        available = _available;
    }  
}

Realmente apreciaría la ayuda.

Estos son los mensajes de error que aparecen en el remix:

Muchas gracias