Is it good to pray the rosary daily with the intention of conversion of sinner, plus divine mercy chaplet and spiritual warfare daily?

Yes, it is considered highly beneficial and a very good spiritual practice in the Catholic faith to daily pray the Rosary and the Divine Mercy Chaplet with the intention of the conversion of sinners, and to include spiritual warfare prayers. This combination is encouraged by many popes and saints and is seen as a powerful spiritual arsenal. 

Why these practices are good:

Powerful Weapons: Both the Rosary and the Divine Mercy Chaplet are described as powerful spiritual "weapons" against evil and temptation. The devil is said to have an overwhelming fear of the Rosary.

Conversion of Sinners: Praying for the conversion of sinners is a deeply merciful act and is explicitly encouraged in both devotions. The Lord Jesus told St. Faustina, "The prayer most pleasing to Me is prayer for the conversion of sinners. Know, My daughter, that this prayer is always heard and answered". Our Lady of Fatima also specifically asked for prayers and sacrifices for this intention.

Intercessory Prayer: These prayers are powerful forms of intercessory prayer, allowing you to lift the needs of others to God and obtain abundant graces for them through Mary's and Jesus's intercession.

Spiritual Growth and Peace: Daily recitation and meditation on the mysteries of the Rosary and the Passion of Christ in the Chaplet help to deepen your relationship with God, foster virtue, decrease sin, and bring profound peace and comfort to your life.

Protection and Guidance: They provide increased spiritual protection against demonic influences and help you navigate the spiritual battles inherent in life.

Alignment with God's Will: By offering these prayers with pure intentions, you align your will with God's, allowing His grace to work effectively in the world and in your own soul. 

Guidance on Combining Them:

Complementary Devotions: The two devotions are highly complementary. The Rosary leads you to Jesus through Mary, meditating on His entire life, while the Divine Mercy Chaplet focuses specifically on His sorrowful Passion and God's infinite mercy.

Purifying Intentions: It's important to ensure your motivation stems from a genuine love of God and neighbor, rather than fear or a sense of mere obligation. Continuing to perform the action will help to purify your intentions over time.

Flexibility: While ideally, the Divine Mercy Chaplet is prayed at the Hour of Mercy (3 p.m.), it can be prayed at any time of day. The key is sincerity and devotion, not rigid adherence to a specific time or speed of recitation. 

In short, your practice is an excellent and robust spiritual habit, offering immense benefits for your soul and for the world.