Xamarin Button border issue

I'm trying to make an app using Xamarin.forms. The problem is that in Android version, button border are displayed, and I would like to remove them. I tried BorderColor="Transparent" but it didn't work.

Also, I've some problems with Text. In fact, I would like to have some padding between Icons and text (for example between F and Facebook). Is there a way to do that ? And how can I handle problems about the size of the text on, for example, iPhone 5 and "Fa...ook" ? I tried to put a smaller police but I guess there is a best solution ?

Here is my Xaml code:

<Grid Margin="0,20,0,0">
    <Grid.ColumnDefinitions>
        <ColumnDefinition Width="*"/>
        <ColumnDefinition Width="*"/>
        <ColumnDefinition Width="*"/>
    </Grid.ColumnDefinitions>
    <Grid.RowDefinitions>
        <RowDefinition Height="100"/>
        <RowDefinition Height="*"/>
        <RowDefinition Height="*"/>
        <RowDefinition Height="*"/>
    </Grid.RowDefinitions>

    <Label Text="Waka'Lokos" Margin="0,20,0,0" HorizontalOptions="Center" FontSize="22.5" TextColor="White" Grid.Row="0" Grid.Column="1"/>
    <Button BackgroundColor="Transparent" FontSize="10" ContentLayout="Top" HorizontalOptions="Center" VerticalOptions="Center" x:Name="fb" Text="Facebook" Grid.Row="1" Grid.Column="0" Image="fb.png" TextColor="#FEF4CA"/>
    <Button BackgroundColor="Transparent" FontSize="10" ContentLayout="Top" HorizontalOptions="Center" VerticalOptions="Center" x:Name="contact" Text="Contact" Grid.Row="1" Grid.Column="1" Image="call.png" TextColor="#FEF4CA"/>
    <Button BackgroundColor="Transparent" FontSize="10" ContentLayout="Top" HorizontalOptions="Center" VerticalOptions="Center" x:Name="insta" Text="Insta" Grid.Row="1" Grid.Column="2" Image="insta.png" TextColor="#FEF4CA"/>
    <Button BackgroundColor="Transparent" FontSize="10" ContentLayout="Top" HorizontalOptions="Center" VerticalOptions="Center" x:Name="chants" Text="Chants" Grid.Row="2" Grid.Column="0" Image="micro.png" TextColor="#FEF4CA"/>
    <Button BackgroundColor="Transparent" FontSize="10" ContentLayout="Top" HorizontalOptions="Center" VerticalOptions="Center" x:Name="communaute" Text="Team" Grid.Row="2" Grid.Column="1" Image="team.png" TextColor="#FEF4CA"/>
    <Button BackgroundColor="Transparent" FontSize="10" ContentLayout="Top" HorizontalOptions="Center" VerticalOptions="Center" x:Name="youtube" Text="Youtube" Grid.Row="2" Grid.Column="2" Image="yt.png" TextColor="#FEF4CA"/>
    <Button BackgroundColor="Transparent" FontSize="10" ContentLayout="Top" HorizontalOptions="Center" VerticalOptions="Center" x:Name="partenaires" Text="Partner" Grid.Row="3" Grid.Column="0" Image="partner.png" TextColor="#FEF4CA"/>
    <Button BackgroundColor="Transparent" FontSize="10" ContentLayout="Top" HorizontalOptions="Center" VerticalOptions="Center" x:Name="plans" Text="Bons Plans" Grid.Row="3" Grid.Column="1" Image="money.png" TextColor="#FEF4CA"/>
    <Button BackgroundColor="Transparent" FontSize="10" ContentLayout="Top" HorizontalOptions="Center" VerticalOptions="Center" x:Name="agenda" Text="Agenda" Grid.Row="3" Grid.Column="2" Image="agenda.png" TextColor="#FEF4CA"/>
</Grid>